High resolution low power consumption OLED display with extended lifetime

ABSTRACT

Full-color pixel arrangements for use in devices such as OLED displays are provided, in which multiple sub-pixels are configured to emit different colors of light, with each sub-pixel having a different optical path length than some or all of the other sub-pixels within the pixel.

PRIORITY

This application is a continuation-in-part of U.S. application Ser. No.14/698,352, filed Apr. 28, 2015, which claims the benefit of U.S.Provisional Patent Application Ser. Nos. 62/003,269, filed May 27, 2014;62/005,343, filed May 30, 2014; 62/026,494, filed Jul. 18, 2014; and62/068,281, filed Oct. 24, 2014, and which is a continuation-in-part ofU.S. application Ser. No. 14/605,876, filed Jan. 26, 2015, which is acontinuation-in-part of U.S. application Ser. No. 14/333,756, filed Jul.17, 2014, which is a continuation-in-part of U.S. application Ser. No.14/243,145, filed Apr. 2, 2014, which is a continuation-in-part of U.S.application Ser. No. 13/744,581, filed Jan. 18, 2013, the disclosure ofeach of which is incorporated by reference in its entirety.

The claimed invention was made by, on behalf of, and/or in connectionwith one or more of the following parties to a joint universitycorporation research agreement: Regents of the University of Michigan,Princeton University, The University of Southern California, and theUniversal Display Corporation. The agreement was in effect on and beforethe date the claimed invention was made, and the claimed invention wasmade as a result of activities undertaken within the scope of theagreement.

FIELD OF THE INVENTION

The present invention relates to light emitting devices such as OLEDdevices and, more specifically, to devices that include full-color pixelarrangements that have pixel arrangements that include not more than twocolors of emissive regions and/or four colors of sub-pixels, and toOLEDs and other devices incorporating the same.

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting devices (OLEDs), organic phototransistors, organic photovoltaiccells, and organic photodetectors. For OLEDs, the organic materials mayhave performance advantages over conventional materials. For example,the wavelength at which an organic emissive layer emits light maygenerally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full colordisplay. Industry standards for such a display call for pixels adaptedto emit particular colors, referred to as “saturated” colors. Inparticular, these standards call for saturated red, green, and bluepixels. Color may be measured using CIE coordinates, which are wellknown to the art.

One example of a green emissive molecule is tris(2-phenylpyridine)iridium, denoted Ir(ppy)3, which has the following structure:

In this, and later figures herein, we depict the dative bond fromnitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between. As used herein, two layers or regions may bedescribed as being disposed in a “stack” when at least a portion of onelayer or region is disposed over at least a portion of the other.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled inthe art, a first “Highest Occupied Molecular Orbital” (HOMO) or “LowestUnoccupied Molecular Orbital” (LUMO) energy level is “greater than” or“higher than” a second HOMO or LUMO energy level if the first energylevel is closer to the vacuum energy level. Since ionization potentials(IP) are measured as a negative energy relative to a vacuum level, ahigher HOMO energy level corresponds to an IP having a smaller absolutevalue (an IP that is less negative). Similarly, a higher LUMO energylevel corresponds to an electron affinity (EA) having a smaller absolutevalue (an EA that is less negative). On a conventional energy leveldiagram, with the vacuum level at the top, the LUMO energy level of amaterial is higher than the HOMO energy level of the same material. A“higher” HOMO or LUMO energy level appears closer to the top of such adiagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled inthe art, a first work function is “greater than” or “higher than” asecond work function if the first work function has a higher absolutevalue. Because work functions are generally measured as negative numbersrelative to vacuum level, this means that a “higher” work function ismore negative. On a conventional energy level diagram, with the vacuumlevel at the top, a “higher” work function is illustrated as furtheraway from the vacuum level in the downward direction. Thus, thedefinitions of HOMO and LUMO energy levels follow a different conventionthan work functions.

Layers, materials, regions, and devices may be described herein inreference to the color of light they emit. In general, as used herein,an emissive region that is described as producing a specific color oflight may include one or more emissive layers disposed over each otherin a stack.

As used herein, a “red” layer, material, region, or device refers to onethat emits light in the range of about 580-700 nm; a “green” layer,material, region, or device refers to one that has an emission spectrumwith a peak wavelength in the range of about 500-600 nm; a “blue” layer,material, or device refers to one that has an emission spectrum with apeak wavelength in the range of about 400-500 nm; and a “yellow” layer,material, region, or device refers to one that has an emission spectrumwith a peak wavelength in the range of about 540-600 nm. In somearrangements, separate regions, layers, materials, regions, or devicesmay provide separate “deep blue” and a “light blue” light. As usedherein, in arrangements that provide separate “light blue” and “deepblue”, the “deep blue” component refers to one having a peak emissionwavelength that is at least about 4 nm less than the peak emissionwavelength of the “light blue” component. Typically, a “light blue”component has a peak emission wavelength in the range of about 465-500nm, and a “deep blue” component has a peak emission wavelength in therange of about 400-470 nm, though these ranges may vary for someconfigurations. Similarly, a color altering layer refers to a layer thatconverts or modifies another color of light to light having a wavelengthas specified for that color. For example, a “red” color filter refers toa filter that results in light having a wavelength in the range of about580-700 nm. In general, there are two classes of color altering layers:color filters that modify a spectrum by removing unwanted wavelengths oflight, and color changing layers that convert photons of higher energyto lower energy. A component “of a color” refers to a component that,when activated or used, produces or otherwise emits light having aparticular color as previously described. For example, a “first emissiveregion of a first color” and a “second emissive region of a second colordifferent than the first color” describes two emissive regions that,when activated within a device, emit two different colors as previouslydescribed.

In some cases, it may be preferable to describe the color of a componentsuch as an emissive region, sub-pixel, color altering layer, or thelike, in terms of 1931 CIE coordinates. For example, a yellow emissivematerial may have multiple peak emission wavelengths, one in or near anedge of the “green” region, and one within or near an edge of the “red”region as previously described. Accordingly, as used herein, each colorterm also corresponds to a shape in the 1931 CIE coordinate color space.The shape in 1931 CIE color space is constructed by following the locusbetween two color points and any additional interior points. Forexample, interior shape parameters for red, green, blue, and yellow maybe defined as shown below and as illustrated in FIG. 75:

Color CIE shape parameters Central Red Locus: [0.6270, 0.3725]; [0.7347,0.2653]; Interior: [0.5086, 0.2657] Central Green Locus: [0.0326,0.3530]; [0.3731, 0.6245]; Interior: [0.2268, 0.3321] Central BlueLocus: [0.1746, 0.0052]; [0.0326, 0.3530]; Interior: [0.2268, 0.3321]Central Yellow Locus: [0.3731, 0.6245]; [0.6270, 0.3725]; Interior:[0.3700, 0.4087]; [0.2886, 0.4572]Thus, for example, a “red” emissive region will emit light having CIEcoordinates within the triangle formed by the vertices[0.6270,0.3725];[0.7347,0.2653]:[0.5086,0.2657]. Where the line betweenpoints [0.6270,0.3725] and [0.7347,0.2653] follows the locus of the 1931color space. More complex color space regions can similarly be defined,such as the case with the green region. The color of the component istypically measured perpendicular to the substrate.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

SUMMARY OF THE INVENTION

Various embodiments disclosed herein provide devices, such as OLEDdisplays, and techniques for the fabrication thereof, which include alimited number of emissive regions, while still being capable ofproviding sufficient color range to provide full-color displays andsimilar devices.

In an embodiment, a full-color pixel arrangement for a device such as anOLED display is provided. The arrangement includes a plurality ofpixels, each of which includes sub-pixels having emissive regions andoptical path lengths, where at least two sub-pixels have differentoptical path lengths. The full-color pixel arrangement may includeemissive regions of exactly two colors. The emissive regions may bedisposed laterally adjacent to one another over the substrate. Thefull-color pixel arrangement may include four or more sub-pixels. Eachsub-pixel may have a different optical path length, or some sub-pixelsmay have the same optical path length. Each pixel may include multiplesub-pixels configured to emit different colors of light, where eachsub-pixel may have a different optical path length than some or all ofthe others. The arrangement may include two, three, four, or moresub-pixels. More generally, the full-color pixel arrangement may includeN total sub-pixels having an emissive region of a first color, with 0 toN−1 color altering layers and/or N+1 or N+2 total sub-pixels. Differentoptical path lengths may be provided by layers having differentthicknesses within each sub-pixel, such as transport or blocking layersof different thicknesses, or by a patterned electrode, such as apatterned anode, disposed under the emissive regions of the sub-pixels.Different portions of the patterned electrode may have differentthicknesses, such that portions of the electrode that serve as anelectrode for each sub-pixel stack have different thicknesses. In someembodiments, the total thickness of organic layers within each sub-pixelmay be the same, and/or the thicknesses of the same type of organiclayer within each sub-pixel may be the same as in some or all of theother sub-pixels. The full-color pixel arrangement may include no coloraltering layers such as color filters. Emissive regions in thesub-pixels may include one or more emissive materials, which may beincluded in a single emissive layer.

Arrangements disclosed herein may be incorporated into a wide variety ofdevices, such as a wearable device, a flat panel display, a computermonitor, a medical monitor, a television, a billboard, a light forinterior or exterior illumination, a signal, a color tunable or colortemperature tunable lighting source, a heads-up display, a 3D display, afully transparent display, a flexible display, a laser printer, atelephone, a cell phone, a personal digital assistant (PDA), a laptopcomputer, a digital camera, a camcorder, a viewfinder, a micro-display,a vehicle, a large area wall, a theater or stadium screen, and a sign.Such devices may have relatively high resolutions, such as at least 250dpi, 500 dpi, or even greater than 1000 dpi.

In an embodiment, a method of fabricating a pixel arrangement isprovided, in which a transparent layer is constructed having at leastone optical characteristic, such as the optical path length orthickness, or the index of refraction, which is different in differentregions of the layer, each of which may correspond to differentsub-pixels within the display. The layer may be disposed in thearrangement as part of an electrode stack.

In an embodiment, a method of fabricating a pixel arrangement isprovided, in which a patterned layer is fabricated over a substrate soas to define at least two non-overlapping sub-pixel regions over thesubstrate. First and second emissive materials may be deposited overfirst and second regions defined by the pattern, and an electrode may befabricated over the emissive materials. The various layers of thearrangement may be fabricated such that the sub-pixel regions havedifferent optical paths between the substrate and the electrode layer.The patterned layer may be a layer deposited over or as a part of anelectrode layer disposed over the substrate and below the patternedlayer. Fabricating the patterned layer also may be performed bypatterning an existing electrode layer disposed over the substrate, suchas by a photolithographic or similar technique.

In an embodiment, a pixel arrangement may include multiple sub-pixels,where at least one layer in each sub-pixel has a different thicknessthan the same layer in each other sub-pixel. The arrangement may includeemissive regions of not more than two colors.

In an embodiment, a pixel arrangement including multiple sub-pixels maybe fabricated by fabricating a plurality of layers over a substrate, atleast one layer in each sub-pixel having a different thickness than thesame layer in each of the other sub-pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer.

FIG. 3 shows a schematic illustration of an example masking arrangementsuitable for fabricating a pixel arrangement as disclosed herein.

FIG. 4 shows a schematic illustration of a pixel arrangement accordingto an embodiment disclosed herein.

FIG. 5 shows a schematic illustration of a pixel arrangement accordingto an embodiment disclosed herein.

FIG. 6 shows a schematic illustration of a pixel arrangement accordingto an embodiment disclosed herein.

FIG. 7 shows a schematic illustration of an example masking arrangementsuitable for fabricating a pixel arrangement as disclosed herein.

FIG. 8 shows a schematic illustration of a pixel arrangement accordingto an embodiment disclosed herein.

FIG. 9 shows a schematic illustration of an example masking arrangementsuitable for fabricating a pixel arrangement as disclosed herein.

FIG. 10 shows a schematic illustration of a pixel arrangement accordingto an embodiment disclosed herein.

FIG. 11 shows the 1931 CIE diagram that highlights a set of pointsoutside the RG line according to an embodiment disclosed herein.

FIG. 12 shows the 1931 CIE diagram with coordinates for pure red, green,and blue, and for a multi-component yellow source that lies outside theRG line according to an embodiment disclosed herein.

FIG. 13 illustrates an example color point rendered without the use of ared sub-pixel according to an embodiment disclosed herein.

FIG. 14 shows a CIE diagram that identifies red, green, blue, and yellowpoints, an established white point, and various color regions accordingto an embodiment disclosed herein.

FIG. 15 shows a schematic illustration of a pixel arrangement includinga blue color change layer disposed over a blue emissive region accordingto an embodiment disclosed herein.

FIG. 16 shows a schematic illustration of a pixel arrangement includinga blue color change layer disposed over a blue emissive region accordingto an embodiment disclosed herein.

FIG. 17 shows a schematic illustration of a pixel arrangement includinga blue color change layer disposed over a blue emissive region accordingto an embodiment disclosed herein.

FIG. 18 shows a diagram that identifies red, green, blue and yellowpoints and associated color spaces, according to an embodiment disclosedherein.

FIG. 19 shows another diagram that identifies red, green, blue andyellow points and associated color spaces, according to an embodimentdisclosed herein.

FIG. 20A shows a color space defined by two sub-pixels, according to anembodiment disclosed herein.

FIG. 20B shows a color space defined by a single sub-pixel, according toan embodiment disclosed herein.

FIGS. 21A and 21B show top-emission (TE) and bottom-emission (BE)configurations to achieve an arrangement as disclosed herein,respectively.

FIGS. 22A and 22B show top- and bottom-emission devices, respectively,in which an additional masking step is used to deposit an additionalthickness of hole transport (HTL) or electron blocking layer (EBL)according to an embodiment.

FIGS. 23A and 23B show top- and bottom-emission devices, a configurationin which the anodes may be patterned separately to individually optimizeemission from each sub-pixel according to an embodiment.

FIG. 24 shows an example schematic arrangement in which yellowsub-pixels are located in a separate plane with respect to the substrateand blue sub-pixels according to an embodiment.

FIG. 25 shows an example arrangement in which there are multiple yellow,red, and green sub-pixels in each pixel that includes a single bluesub-pixel according to an embodiment.

FIG. 26 shows an example device configuration having two planes ofsub-pixels according to an embodiment.

FIG. 27 shows an example top-emitting device configuration having twoplanes of sub-pixels according to an embodiment.

FIG. 28A shows an example OLED deposition according to an embodiment.FIG. 28B shows the corresponding pixelated mask, in which the unshadedareas correspond to openings in the mask.

FIG. 29A shows an example sub-pixel emissive material layout accordingto an embodiment, in which sub-pixels of the same color are groupedtogether in adjacent pixels on the same row. FIG. 29B shows thecorresponding pixelated mask arrangement.

FIGS. 30A and 30B show an example sub-pixel layout and correspondingpixelated mask, respectively, according to an embodiment.

FIG. 31 shows an example sub-pixel layout according to an embodiment.

FIG. 32 shows an example mask design to implement such a configuration.

FIG. 33 shows another example of a staggered layout according to anembodiment.

FIG. 34 shows an example mask arrangement corresponding to the layout ofFIG. 33.

FIG. 35 shows an example of data line formation according to anembodiment.

FIG. 36 shows an example arrangement according to an embodiment.

FIG. 37 shows a variation on the arrangement shown in FIG. 36 in whichthe blue and yellow sub-pixels may be deposited in pairs according to anembodiment.

FIG. 38 shows another example arrangement according to an embodiment, inwhich each mask opening is used to deposit on 4 sub-pixels of the samecolor at the same time.

FIG. 39 shows an example arrangement according to an embodiment in whichfour neighboring blue sub-pixels are replaced by a single largesub-pixel, relative to the arrangement shown in FIG. 38, according to anembodiment.

FIG. 40 shows an example arrangement of a scan and data line layout forthe sub-pixel arrangement of FIG. 39 according to an embodiment.

FIG. 41 shows an example RGB1B2Y arrangement according to an embodiment.

FIG. 42A shows an example variant of the arrangement in FIG. 41, inwhich four of the deep blue sub-pixels are replaced with a single largedeep blue sub-pixel to be shared by four pixels according to anembodiment.

FIG. 42B shows an example arrangement similar to the arrangement of FIG.42A, which may be more suited for efficient deposition via OVJP andsimilar printing techniques.

FIG. 43 shows a configuration according to an embodiment, which may besuitable for wearable devices and similar applications.

FIG. 44 shows red, green and blue points on a CIE chart and a desiredyellow (“Yellow 1”) according to an embodiment.

FIG. 45 shows a comparison of an example conventional RGB side-by-sidepixel layout to an arrangement as disclosed herein that uses only twoOLED emissive region depositions.

FIG. 46 shows an example arrangement according to an embodiment in whicha green color altering layer is disposed over a light blue (“LB”)sub-pixel.

FIG. 47 shows an arrangement according to an embodiment in which a greencolor altering layer is disposed over both the light blue and yellowemissive regions to produce the green sub-pixel according to anembodiment.

FIG. 48 shows an arrangement according to an embodiment in which a greencolor altering layer is disposed over deep blue and yellow emissiveregions.

FIG. 49 shows an example arrangement according to an embodiment in whichthe display requires only 3 TFT circuits per pixel, and in which no deepblue sub-pixels are present.

FIG. 50 shows an example arrangement in which a green color alteringlayer is disposed over a light blue emissive region to provide the greensub-pixel according to an embodiment.

FIG. 51 shows another example according to an embodiment in which agreen color altering layer is disposed over a light blue emissive regionto provide a green sub-pixel.

FIG. 52 shows an example schematic pixel layout according to anembodiment.

FIG. 53 shows an example schematic pixel layout according to anembodiment.

FIG. 54 shows an example device arrangement according to an embodiment,in which a thin metal layer is disposed above a TCO layer.

FIG. 55 shows simulation data for an embodiment including blue andyellow emissive regions, with the blue region coupled to a microcavity.

FIG. 56 shows an example system and process for rendering display dataaccording to an embodiment.

FIG. 57 shows a schematic representation of an electrode stack for aplurality of sub-pixels according to an embodiment.

FIG. 58 shows a schematic representation of an electrode stack for aplurality of sub-pixels according to an embodiment.

FIG. 59 shows a schematic representation of an electrode stack for aplurality of sub-pixels according to an embodiment.

FIG. 60 shows a schematic representation of an electrode stack for aplurality of sub-pixels according to an embodiment.

FIGS. 61A and 61B show schematic representations of sub-pixelarrangements having different optical path lengths according toembodiments.

FIG. 62 shows an example sub-pixel architecture that provides afour-color subpixel array without any color filters and two colors ofemissive regions according to an embodiment.

FIG. 63A shows a modeled OLED structure according to an embodiment.

FIG. 63B shows 1931 CIE emission as a function of anode thickness for adevice structure as shown in FIG. 63A, with vertical lines and labelsshowing G, R, and Y color points that generate the spectrums in FIG. 64.

FIG. 64 shows modeled normalized emission intensity as a function ofwavelength for a yellow EML according to an embodiment.

FIG. 65 shows a schematic depiction of color space tuning of a yellowsubpixel according to an embodiment.

FIG. 66 shows experimental EL at normal incidence for a yellow EMLcomposed of e-host, h-host, and 2 emitters (1 red and 1 green) tuned tonear DCI P3 green and red colors according to an embodiment.

FIG. 67 shows experimental EL at normal incidence for a yellow EMLcomposed of e-host, h-host, and 2 emitters (1 red and 1 green) tunedfrom yellow to red emission using the HTL thickness cavity equivalent totuning with electrode thickness according to an embodiment.

FIG. 68 shows experimental EL at normal incidence for a yellow EMLcomposed of e-host, h-host, and 1 yellow emitter tuned from yellow tored emission using the HTL thickness cavity equivalent according to anembodiment.

FIG. 69A shows the integrated intensity as a function of angle for ayellow EML composed of e-host, h-host, and 1 green and 1 red emitter ata fixed HTL thickness tuned for red emission according to an embodiment.

FIG. 69B shows angle dependent EL for a yellow EML composed of e-host,h-host, and 1 green and 1 red emitter at a fixed HTL thickness tuned forred emission according to an embodiment.

FIG. 69C shows 1931 CIE as a function of angle for a yellow EML composedof e-host, h-host, and 1 green and 1 red emitter at a fixed HTLthickness tuned for red emission according to an embodiment.

FIG. 69D shows 1931 Δuv as a function of angle for a yellow EML composedof e-host, h-host, and 1 green and 1 red emitter at a fixed HTLthickness tuned for red emission according to an embodiment.

FIG. 70A shows the integrated intensity as a function of angle for ayellow EML composed of e-host, h-host, and 1 yellow emitter at a fixedHTL thickness tuned for red emission according to an embodiment.

FIG. 70B shows the angle dependent EL for a yellow EML composed ofe-host, h-host, and 1 yellow emitter at a fixed HTL thickness tuned forred emission according to an embodiment.

FIG. 70C shows the 1931 CIE coordinates as a function of angle for ayellow EML composed of e-host, h-host, and 1 yellow emitter at a fixedHTL thickness tuned for red emission according to an embodiment.

FIG. 70D shows the 1931 Δuv as a function of angle for a yellow EMLcomposed of e-host, h-host, and 1 yellow emitter at a fixed HTLthickness tuned for red emission according to an embodiment.

FIG. 71A shows integrated intensity as a function of angle for a yellowEML composed of e-host, h-host, and 1 green and 1 red emitter at a fixedHTL thickness tuned for green emission according to an embodiment.

FIG. 71B shows angle dependent EL for a yellow EML composed of e-host,h-host, and 1 green and 1 red emitter at a fixed HTL thickness tuned forgreen emission according to an embodiment.

FIG. 71C shows 1931 CIE as a function of angle for a yellow EML composedof e-host, h-host, and 1 green and 1 red emitter at a fixed HTLthickness tuned for green emission according to an embodiment.

FIG. 71D shows the 1931 Δuv as a function of angle for a yellow EMLcomposed of e-host, h-host, and 1 green and 1 red emitter at a fixed HTLthickness tuned for green emission according to an embodiment.

FIG. 72A shows a modeled EL spectrum of a red sub-pixel at 0 and 60degrees with and without a red color filter according to an embodiment.

FIG. 72B shows the change in color (Δuv) as a function of angle for thered sub-pixel of FIG. 72A with and without the red color filteraccording to an embodiment.

FIG. 73A shows a modeled EL spectrum from a sub-pixel generated from ayellow EML according to an embodiment.

FIG. 73B shows a white EML in the same optical microcavities as thesub-pixel for FIG. 73A at normal incidence.

FIG. 74A shows a modeled EL spectrum from a sub-pixel generated from ayellow EML according to an embodiment.

FIG. 74B shows a white EML in the same optical microcavities as thesub-pixel for FIG. 74A at 60 degrees from normal incidence.

FIG. 75 shows an example CIE diagram with specific color regionsaccording to embodiments disclosed herein.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporatedby reference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 1 shows an organic light emitting device 100. The figures are notnecessarily drawn to scale. Device 100 may include a substrate 110, ananode 115, a hole injection layer 120, a hole transport layer 125, anelectron blocking layer 130, an emissive layer 135, a hole blockinglayer 140, an electron transport layer 145, an electron injection layer150, a protective layer 155, a cathode 160, and a barrier layer 170.Cathode 160 is a compound cathode having a first conductive layer 162and a second conductive layer 164. Device 100 may be fabricated bydepositing the layers described, in order. The properties and functionsof these various layers, as well as example materials, are described inmore detail in U.S. Pat. No. 7,279,704 at cols. 6-10, which areincorporated by reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F₄-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,a cathode 215, an emissive layer 220, a hole transport layer 225, and ananode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2.For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

Unless otherwise specified, any of the layers of the various embodimentsmay be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 toForrest et al., which is incorporated by reference in its entirety, anddeposition by organic vapor jet printing (OVJP), such as described inU.S. Pat. No. 7,431,968, which is incorporated by reference in itsentirety. Other suitable deposition methods include spin coating andother solution based processes. Solution based processes are preferablycarried out in nitrogen or an inert atmosphere. For the other layers,preferred methods include thermal evaporation. Preferred patterningmethods include deposition through a mask, cold welding such asdescribed in U.S. Pat. Nos. 6,294,398 and 6,468,819, which areincorporated by reference in their entireties, and patterning associatedwith some of the deposition methods such as ink-jet and OVJD. Othermethods may also be used. The materials to be deposited may be modifiedto make them compatible with a particular deposition method. Forexample, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processibility than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the presentinvention may further optionally comprise a barrier layer. One purposeof the barrier layer is to protect the electrodes and organic layersfrom damaging exposure to harmful species in the environment includingmoisture, vapor and/or gases, etc. The barrier layer may be depositedover, under or next to a substrate, an electrode, or over any otherparts of a device including an edge. The barrier layer may comprise asingle layer, or multiple layers. The barrier layer may be formed byvarious known chemical vapor deposition techniques and may includecompositions having a single phase as well as compositions havingmultiple phases. Any suitable material or combination of materials maybe used for the barrier layer. The barrier layer may incorporate aninorganic or an organic compound or both. The preferred barrier layercomprises a mixture of a polymeric material and a non-polymeric materialas described in U.S. Pat. No. 7,968,146, PCT Pat. Application Nos.PCT/US2007/023098 and PCT/US2009/042829, which are herein incorporatedby reference in their entireties. To be considered a “mixture”, theaforesaid polymeric and non-polymeric materials comprising the barrierlayer should be deposited under the same reaction conditions and/or atthe same time. The weight ratio of polymeric to non-polymeric materialmay be in the range of 95:5 to 5:95. The polymeric material and thenon-polymeric material may be created from the same precursor material.In one example, the mixture of a polymeric material and a non-polymericmaterial consists essentially of polymeric silicon and inorganicsilicon.

Devices fabricated in accordance with embodiments of the invention maybe incorporated into a wide variety of consumer products, including flatpanel displays, computer monitors, medical monitors, televisions,billboards, lights for interior or exterior illumination and/orsignaling, color tunable or color temperature tunable lighting sources,heads up displays, fully transparent displays, flexible displays, laserprinters, telephones, cell phones, personal digital assistants (PDAs),laptop computers, digital cameras, camcorders, viewfinders,micro-displays, vehicles, a large area wall, theater or stadium screen,or a sign. Various control mechanisms may be used to control devicesfabricated in accordance with the present invention, including passivematrix and active matrix. Many of the devices are primarily intended foruse in a temperature range comfortable to humans, such as 18 degrees C.to 30 degrees C., and more preferably at room temperature (20-25 degreesC.), but can operate at temperatures outside this range, such as −40 Cto +85 C or higher.

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures.

The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl,heterocyclic group, aryl, aromatic group, and heteroaryl are known tothe art, and are defined in U.S. Pat. No. 7,279,704 at cols. 31-32,which are incorporated herein by reference.

Current display architectures and manufacturing capabilities typicallydo not allow for low power consumption and high resolution OLEDdisplays. For example, side by side (SBS) architecture typically canachieve relatively low power consumption (and therefore good lifetime),but this architecture may require relatively high resolution shadowmasking. Such techniques often are limited to around 250 dpi resolution.To achieve higher resolutions, architectures using white devices inconjunction with color filters may be used to avoid patterning the OLEDemissive layers. However, such techniques typically suffer fromrelatively lower efficiency and therefore higher power consumption,which also reduces lifetime. These constraints may be somewhat overcomeby employing a RGBW pixel architecture that uses both an unfilteredwhite sub-pixel and devices that emit at individual colors by employingcolor filters over other white sub-pixels. This architecture generallyis considered to result in poorer image quality, and typically still hasa lower power consumption and poorer lifetime than a comparable RGB SBSdisplay.

The present disclosure provides arrangements of pixel components thatallow for full-color devices, while using emissive devices that emit notmore than two colors, and/or a limited number of color altering layers.Embodiments disclosed herein may provide improved performance overconventional RGBW displays, such as lower power consumption and longerlifetime, with fewer high resolution masking steps, and at a lowerresolution, in comparison to a conventional RGB SBS display That is,although an arrangement as disclosed herein may include any number ofsub-pixels or other emissive devices or regions, within the arrangementthere may be a limited number of colors emitted by emissive devices orregions within the arrangement. As a specific example, an arrangement asdisclosed herein may include three sub-pixels. Two of the sub-pixels mayinclude emissive regions, such as OLEDs, that emit light of the samecolor, with one of the sub-pixels being filtered or otherwise modifiedto produce a different color after light is emitted by the emissiveregion. The third sub-pixel may include an emissive region that emitslight of a different color than the first emissive regions within thetwo sub-pixels. Thus, although the sub-pixels overall may produce lightof three or more colors, the emissive regions within the arrangementneed only initially emit light of two colors. Devices disclosed hereinalso may be achieved using simplified fabrication techniques compared toconventional SBS arrangements, because fewer masking steps may berequired.

In an embodiment, two masking steps may be used. This may provide forsimplified fabrication when compared to the three masking steps requiredfor a conventional RGB SBS display. Each mask opening area may beapproximately half the pixel area, as opposed to a third in aconventional SBS display. The increased area of the shadow mask openingrelative to a conventional SBS display of the same pixel size may allowfor higher pixel density. For example, the same size opening will allowfor up to about a 50% increase in display resolution compared to aconventional SBS technique. In some configurations, the exact size ofthe mask openings may be determined based upon lifetime matchingconsiderations, such as to optimize current flow through each sub-pixeland thus improve overall display lifetime.

An increase in fill factor also may also be possible using techniquesdisclosed herein, particularly for top emitting active matrix OLED(AMOLED) displays, which may allow for higher efficiency relative to aconventional three-mask pixilation approach of the same resolution. Thisis due to the relatively increased area of the three sub-pixels in atwo-mask approach as disclosed, compared to a conventional three-maskapproach. With a two-mask approach as disclosed, less current may berequired for at least some sub-pixels, to render the same luminance froma display. This may result in higher device efficiency, lower voltage,and/or longer display lifetime.

FIG. 3 shows a schematic illustration of an example masking arrangementsuitable for fabricating a pixel arrangement as disclosed herein. In afirst masked deposition, an emissive layer structure, or a stackeddevice structure including multiple emissive layers, may be deposited ina first region 310. The first region contains one or more emissivelayers that emit light of a first color. A second masked deposition maybe performed in an adjacent or otherwise nearby region 320, to depositan emissive layer or stacked structure that emits light of a secondcolor different from the first. Two color altering layers 330, 340, maythen be disposed over the second emissive region, such that lightpassing through each filter may be converted from the second color tothird and fourth colors, respectively, each different from the first andsecond. In some configurations, a portion of the second emissive regionmay be left uncovered, such that the illustrated arrangement may providelight having four distinct colors. In some configurations, the coloraltering layers 330, 340 may cover the entirety of the second region,such that the illustrated arrangement provides light of three distinctcolors. Although shown as disposed with some distance between them inFIG. 3 for illustration purposes, it will be understood that in generalthe color filters may be disposed immediately adjacent to one another,such that no yellow light is emitted in the region between the filters.Similarly, each filter may extend to the appropriate edges of the yellowemissive region, such that no yellow light is emitted from the edgeimmediately adjacent to the color altering layer. Each of the emissivelayers or stacked structures may include one or more emissive materials,each of which may be phosphorescent or fluorescent. More generally, eachemissive material may include any of the emissive materials, layers,and/or structures disclosed herein.

As a specific example, the first mask deposition 310 may provide a bluedevice, which may be a single EML structure or a stacked devicecontaining more than one EML. As is known in the art, a stacked devicemay be desirable to provide extended lifetime and/or reduced imagesticking; in other arrangements, a single-layer emissive device may bepreferred to reduce fabrication cost and complexity. The blue OLED maybe phosphorescent or fluorescent. The second mask deposition 320 mayprovide a yellow device, which may be made, for example, by combiningred and green emitters. More generally, the yellow device may beprovided using any suitable combination of emissive materials and/orlayers. As specific examples, separate red and green emitters may beprovided in one mixed layer; in separate layers within a two-EML device,in which they may be in direct contact or separated by one or more otherlayers or materials; in a stacked device with a red EML in one OLEDwithin the stack and a green EML in the other; in a yellow device usinga single EML containing a yellow emitter; or in a stacked devicecontaining two yellow EMLs. Similarly, a yellow device may be providedby more than two emissive materials and/or layers, such as red, green,and yellow emissive materials, which may be configured in any suitablearrangements, including in a single mixed layer, in separate layerswithin a multi-EML device in which they may be in direct contact or not;in a stacked device with red, green, and yellow EMLs in OLEDs within thestack, or the like. Thus, in some configurations, an emissive region maybe provided by multiple emissive materials, each of which has anemission spectrum or peak emission wavelength that differs from theultimate color of the region as a whole. Various combinations also maybe used, though advantageously any selected combination may be depositedusing the same second mask arrangement. In the completed exampleconfiguration, the blue device is controlled by one anode and associatedactive matrix control circuit. The yellow device is divided into threesub-pixels, yellow, green and red. Each sub-pixel is then controlled byits own anode and associated active matrix control circuit. The yellowsub-pixel uses the unfiltered yellow light from the yellow OLED. Thegreen sub-pixel is obtained by placing a green color filter over theyellow OLED, and, similarly, a red sub-pixel is obtained by placing ared color filter over the yellow OLED. Thus, the resulting pixelarrangement has four sub-pixels, red, green, blue, and yellow (RGBY).Such an arrangement may be advantageous, because the blue performancemay not be limited by a color filter as in a conventional RGBW display,but may have the same optimized lifetime as in a conventional RGB SBSdisplay. Further, in a conventional RGBW arrangement, the green colorfilter is configured to prevent transmission of as much blue and redlight as possible. Thus, a band-pass filter typically is used as thegreen color filter. In an RGBY arrangement as disclosed herein whereyellow light is used as a multi-component light source, the green colorfilter may be configured to prevent transmission only of red light sincethe multi-component light does not include a blue component. Thus, acut-off filter may be used instead of a band-pass filter, which mayprovide relatively greater efficiency and color saturation.

Embodiments disclosed herein may use unfiltered yellow light to improvedisplay efficiency at times when highly saturated red or green is notrequired. In operation, the unfiltered yellow device may be used in asimilar manner to white in conventional a RGBW display, and similaralgorithms may be employed for signal processing. To render a specificunsaturated color, yellow light can be mixed with the three individualprimary red, green or blue colors, which may provide higher efficiencythan just using the red, green or blue primary colors alone. Afull-color display using this technique may have only about a 12% higherpower consumption than a conventional SBS RGB arrangement, in contrastto a conventional RGBW arrangement which typically has about a 50%higher power consumption than the SBS RGB arrangement. This level ofpower reduction may be achieved even if the overall red and greensub-pixel efficiency is reduced by 25%. For example, color filters mayreduce the efficiency for the red and green alone by 50%, but theunfiltered yellow sub-pixel may restore much of this loss.

Embodiments disclosed herein similarly may allow for increased displaycolor range. For example, referring to FIG. 11, a yellow multi-componentsource may be configured such that it emits light having CIE coordinatesthat lie on the “RG line” between the identified pure red and greenpoints, such as the illustrated point 1104. In some embodiments, theidentified red and green points may correspond to the “pure” colorsemitted by emissive regions in the corresponding sub-pixels.Alternatively, the yellow multi-component source may be configured toemit light that lies outside the RG line, such as point 1108, any pointalong the illustrated curve 1100, or the like. The use of such amulti-component source may increase the available display color gamut,by allowing for use of the CIE region outside the RG line. The increasein color gamut may be achieved or used when the yellow multi-componentsource is filtered to provide red and/or green light, or it may be usedwhen the yellow source is used unfiltered, according to the variousarrangements disclosed herein. Thus, in some configurations, it may bedesirable for the yellow multi-component source to have CIE coordinatesthat lie outside the RG line on the 1931 CIE diagram.

FIG. 4 shows a schematic illustration of a pixel arrangement accordingto an embodiment disclosed herein. As described with respect to FIG. 3,the arrangement includes four sub-pixels 410, 420, 430, 440. Onesub-pixel 410 includes one or more emissive devices or regions that emitlight of a first color. The other sub-pixels 420, 430, 440 areconstructed using emissive regions that emit light of a second color. Acolor altering layer 432, 442 may be disposed over each of two of theemissive regions 434, 444. The third sub-pixel 420 is left unfiltered,resulting in a pixel arrangement that has four sub-pixels, eachproviding light of a different color.

In some configurations, additional color altering layers may be used.For example, a blue color altering layer may be disposed over the blueemissive region 410 to modify the spectral output resulting at the bluesub-pixel. An example of such a configuration is shown in FIG. 15, inwhich a blue color altering layer is disposed over the blue emissiveregion, while the other emissive regions and color altering layers arethe same as shown in FIG. 4. Although shown generally as a blue coloraltering layer and a blue emissive region for clarity, the blue coloraltering layer may be a light blue or deep blue color altering layer.Similarly, the blue emissive region may be a deep blue or light blueemissive region.

As described with respect to FIG. 3, each sub-pixel may be controlled byan associated control circuit. Example control circuits are shown inFIG. 4 for purposes of illustration, with various control elementsshaded to match the controlled emissive regions. The specificarrangement of control circuitry is provided by way of example only, andany suitable control circuitry may be used as will be readily apparentto one of skill in the art.

In general parlance in the art, a “sub-pixel” may refer to the emissiveregion, which may be a single-layer EML, a stacked device, or the like,in conjunction with any color altering layer that is used to modify thecolor emitted by the emissive region. For example, the sub-pixel 430includes an emissive region 434 and a color altering layer 432. As usedherein, the “emissive region” of a sub-pixel refers to any and allemissive layers, regions, and devices that are used initially togenerate light for the sub-pixel. A sub-pixel also may includeadditional layers disposed in a stack with the emissive region thataffect the color ultimately produced by the sub-pixel, such as coloraltering layers disclosed herein, though such color altering layerstypically are not considered “emissive layers” as disclosed herein. Anunfiltered sub-pixel is one that excludes a color modifying componentsuch as a color altering layer, but may include one or more emissiveregions, layers, or devices.

In some configurations, an “emissive region” may include emissivematerials that emit light of multiple colors. For example, a yellowemissive region may include multiple materials that emit red and greenlight when each material is used in an OLED device alone. When used in ayellow device, the individual materials typically are not arranged suchthat they can be individually activated or addressed. That is, the“yellow” OLED stack containing the materials cannot be driven to producered, green, or yellow light; rather, the stack can be driven as a wholeto produce yellow light. Such an emissive region may be referred to as ayellow emissive region even though, at the level of individual emitters,the stack does not directly produce yellow light. As described infurther detail below, the individual emissive materials used in anemissive region (if more than one), may be placed in the same emissivelayer within the device, or in multiple emissive layers within an OLEDdevice comprising an emissive region. As described in further detailbelow, embodiments disclosed herein may allow for OLED devices such asdisplays that include a limited number of colors of emissive regions,while including more colors of sub-pixels or other OLED devices than thenumber of colors of emissive regions. For example, a device as disclosedherein may include only blue and yellow emissive regions. Additionalcolors of sub-pixels may be achieved by the use of color alteringlayers, such as color altering layers disposed in a stack with yellow orblue emissive regions, or more generally through the use of coloraltering layers, electrodes or other structures that form a microcavityas disclosed herein, or any other suitable configuration. In some cases,the general color provided by a sub-pixel may be the same as the colorprovided by the emissive region in the stack that defines the sub-pixel,such as where a deep blue color altering layer is disposed in a stackwith a light blue emissive region to produce a deep blue sub-pixel.Similarly, the color provided by a sub-pixel may be different than thecolor provided by an emissive region in the stack that defines thesub-pixel, such as where a green color altering layer is disposed in astack with a yellow emissive region to product a green sub-pixel.

In some configurations, emissive regions and/or emissive layers may spanmultiple sub-pixels, such as where additional layers and circuitry arefabricated to allow portions of an emissive region or layer to beseparately addressable.

An emissive region as disclosed herein may be distinguished from anemissive “layer” as typically referred to in the art and as used herein.In some cases, a single emissive region may include multiple layers,such as where a yellow emissive region is fabricated by sequentially redand green emissive layers to form the yellow emissive region. Aspreviously described, when such layers occur in an emissive region asdisclosed herein, the layers are not individually addressable within asingle emissive stack; rather, the layers are activated or drivenconcurrently to produce the desired color of light for the emissiveregion. In other configurations, an emissive region may include a singleemissive layer of a single color, or multiple emissive layers of thesame color, in which case the color of such an emissive layer will bethe same as, or in the same region of the spectrum as, the color of theemissive region in which the emissive layer is disposed.

In some configurations, fewer sub-pixels may be used to achieve afull-color device or pixel arrangement. FIG. 5 shows an examplearrangement that uses three sub-pixels 510, 520, 530. Similarly to theexample shown in FIG. 4, a first sub-pixel 510 may be created bydepositing one or more emissive regions through a mask, in a singleemissive layer or a stacked arrangement, and leaving the resultingsub-pixel unfiltered. The other two sub-pixels 520, 530, may bedeposited during a single masked deposition. As previously described,each may include one or more emissive materials and/or layers, and maybe individual emissive layers or stacked devices. A color altering layer532 may then be disposed over one or more of the emissive regions, toresult in a full-color arrangement having three sub-pixels of differentcolors.

As a specific example, the two masking steps may be blue and green. Thatis, in a first masked deposition technique, a blue layer or stack may bedeposited in a region corresponding to the first sub-pixel 510. Greenlayers or stacked devices may be deposited in regions corresponding tothe second and third sub-pixels 520, 530 in a second masked deposition.The green sub-pixel 520 provides unfiltered green light. The redsub-pixel 530 uses a color altering layer 532, such as a green-to-redcolor changing layer having a relatively high conversion efficiency, toconvert the green light emitted by the green device 530 to red light.Such a configuration may result in a display that with up to 50% higherresolution than a comparable conventional RGB SBS display, with littleor no increase in power consumption or associated decrease in lifetime.Such an approach also may improve the display efficiency by not “losing”as much light due to use of a conventional color filter, instead using acolor changing layer to provide the third color.

As another example, a blue color altering layer may be disposed over theblue emissive region as previously described. Such a configuration isshown in FIG. 16. As previously described, the blue color altering layermay be a light blue or deep blue color altering layer, and the blueemissive region may be a deep blue or light blue emissive region.

FIG. 6 shows a schematic illustration of a configuration in which thetwo masking steps are blue and yellow, i.e., one or more blue emissivelayers are deposited during one masked deposition, and one or moreyellow emissive layers are deposited during another. As with FIG. 6, theillustrated configuration uses only three sub-pixels, red, green, andblue. In this example, the green sub-pixel uses a green color filter toconvert light from the yellow OLED to green, the red sub-pixel uses ared color filter to convert light from the yellow OLED to red, and theblue sub-pixel uses unfiltered light from the blue OLED. Similarconfigurations may use color altering layers other than or in additionto the specific color filters shown.

As another example, a blue color altering layer may be disposed over theblue emissive region as previously described. Such a configuration isshown in FIG. 17. As previously described, the blue color altering layermay be a light blue or deep blue color altering layer, and the blueemissive region may be a deep blue or light blue emissive region.

In some configurations, the efficiency of one or more sub-pixels may beenhanced by using a color changing layer instead of, or in addition to,a conventional color filter as a color altering layer as disclosedherein. For example, referring to the example shown in FIG. 6, a redcolor changing layer with a relatively high conversion efficiency fromyellow to red may be placed between the yellow OLED and red colorfilter. Such a configuration may enhance the red sub-pixel efficiency.More generally, the use of a color changing layer disposed in a stackwith an OLED, or an OLED and a color filter, may enhance the efficiencyof that sub-pixel.

Other configurations disclosed herein may use additional color alteringlayers, and may include color altering layers disposed over multipleemissive regions or types of emissive region. FIG. 7 shows an examplemasking arrangement that uses emissive regions of two colors, light blue710 and white 720. The masked areas may be used to deposit emissiveregions of each color as previously disclosed. Various color alteringlayers also may be disposed over the resulting emissive regions tocreate a full-color pixel arrangement. In the example shown in FIG. 7, adeep blue color filter 730, a red color filter 740, and a green colorfilter 750 are disposed over corresponding white emissive regions, toform three sub-pixels of those colors, while the light blue emissiveregion remains unfiltered to form a light blue sub-pixel. Such aconfiguration may be used to enhance overall blue lifetime by using thelight blue and deep blue sub-pixels as needed, as described in U.S.Patent Publication No. 2010/0090620, the disclosure of which isincorporated by reference in its entirety. As previously described,other color altering layers may be used in addition to or instead of thespecific color filters described with respect to FIG. 7.

FIG. 8 shows an example pixel arrangement corresponding to thedeposition arrangement shown in FIG. 7. Similarly to the arrangementshown in FIG. 4, the arrangement of FIG. 7 includes an unfilteredsub-pixel 810, and three sub-pixels 820, 830, 840 each of which isformed from an emissive region 821, 831, 841 and a color filter 822,832, 842, respectively. In the example shown in FIG. 7, the unfilteredsub-pixel 810 is a light blue sub-pixel, and the color filters 822, 832,842 are deep blue, red, and green, respectively. The specific emissioncolors and color filters shown are illustrative only, and various othercolors, color altering layers, and combinations may be used withoutdeparting from the scope of embodiments disclosed herein.

In an embodiment, each emissive region deposited during each of twomasked deposition operations may be combined with a color altering layerto form one or more pixels. FIG. 9 shows an example arrangement in whicheach type of emissive region is combined with one or more color alteringlayers to create multiple sub-pixels. For example, the two maskedregions may correspond to a light blue emissive region 910 and a yellowemissive region 920, each of which may be deposited in one of twomasking steps as previously described. A deep blue color altering layer930 may be combined with a light blue emissive region 910 to form a deepblue sub-pixel. Red and green color altering layers 930, 940,respectively, each may be combined with a portion of a yellow emissiveregion to form red and green sub-pixels. A light blue emissive regionalso may be left unfiltered to form a light blue sub-pixel. As describedwith respect to FIG. 7, use of the light and deep blue sub-pixels mayimprove performance and device lifetime. In addition, the relativelylong light blue lifetime can extend overall display operation andprovide improved power efficiency, since the light blue sub-pixel isunfiltered.

FIG. 10 shows a pixel arrangement corresponding to the mask and coloraltering layer arrangement described with respect to FIG. 9. As shown,four sub-pixels are created from two emissive regions of a first color,one of which is unfiltered, and two emissive regions of a second color.Following the example of FIG. 9, a light blue sub-pixel is formed froman unfiltered light blue emissive region, a deep blue sub-pixel isformed from a light blue emissive region and a deep blue color alteringlayer, a red sub-pixel is formed from a yellow emissive region and a redcolor altering layer, and a green sub-pixel is formed from a yellowemissive region and a green color altering layer. The specific emissioncolors and color altering layers shown are illustrative only, andvarious other colors, color altering layers, and combinations may beused without departing from the scope of embodiments disclosed herein.

Various techniques may be used to fabricate the arrangements disclosedherein. In general, it may be desirable for the optical cavity (i.e.,the optimized layer thicknesses in terms of optics from the device,which does not require or refer specifically to a microcavity) for eachcolor to be tuned for that color. However, such a restriction mayrequire each sub-pixel stack to have a different optical path length,adding complexity to the manufacturing process.

For example, FIGS. 21A and 21B show top-emission (TE) andbottom-emission (BE) configurations to achieve an arrangement asdisclosed herein, such as shown, for example, in FIG. 15. In thisarrangement, the transport layers are a common thickness across allsub-pixels. For a top-emission device, the capping layer (CPL) also maybe common to all sub-pixels. The fabrication of an arrangement as shownin FIGS. 21A and 21B may require the use of only two high-resolutionmasks to deposit blue and yellow emissive layers, respectively. Asdescribed in further detail, the various regions of blue and yellowemissive layers may be used as separate emissive regions in separatesub-pixels, which may be the same or different colors. That is, OLEDemissive material deposited during a single deposition step may be usedto create multiple sub-pixels, and multiple colors of sub-pixels, asdisclosed herein.

As another example, FIGS. 22A and 22B show top- and bottom-emissiondevices in which an additional masking step is used to deposit anadditional thickness of material, such as hole transport layer (HTL)material, electron blocking layer (EBL) material, hole injection layer(HIL) material, or the like, between the common HTL and yellow emissivelayer (EML). Such a configuration may increase the external efficiencyof the yellow emissive layer and/or associated sub-pixels. Alternativelyor in addition, the additional masking step may be used to depositadditional ETL and/or HBL material between the yellow EML and the commonelectron transport layer (ETL). As described in further detail below,the use of such additional material may be used to configure a sub-pixelto have an optical path length that is particularly suited to the colorof light emitted by the sub-pixel. Additional masking steps may be usedfor the green and red sub-pixels.

As another example, FIGS. 23A and 23B show a configuration in which theanodes may be patterned separately to individually optimize emissionfrom each sub-pixel. As specific examples, two anodes may be used forthe yellow and blue sub-pixels; or three anodes may be used for yellow,blue, and red or green sub-pixels; or four anodes may be used for theyellow, blue, red, and green sub-pixels. Such configurations mayincrease the efficiencies, lifetimes, and color of each associatedsub-pixel. For a bottom-emission device, these configurations may beachieved by having a thicker TCO. For a top-emitting architecture, metalreflector spacer and/or TCO anodes may be used. In this case thereflector spacer length is part of the pixel optical cavity, soseparately patterning the spacer between the TCO and the reflector metalmay allow the optical cavity to be tuned to a desired color for eachsub-pixel.

It will be understood that a variety of layers are shown in FIGS. 21-23for illustration purposes, but that not all layers shown are required,other layers may be used, and other arrangements of layers may be usedother than as specifically indicated with respect to each example.

As previously indicated, in some embodiments it may be advantageous fordifferent sub-pixels to be “tuned” to a particular color or range ofcolors based upon the optical cavity, which may or may not be amicrocavity, associated with the sub-pixel. In some embodiments, theoptical path length may be different between sub-pixels within a pixel.Various techniques may be used to achieve different optical pathlengths, i.e., different optical thicknesses, such that each displaycolor (e.g., red, green, blue and yellow) can have a specific opticalthickness that may improve or optimize the resulting color andefficiency. In some embodiments, these approaches are independent of, ordo not negatively affect, the patterning requirements for the emissivelayers or the resolution required for the masked deposition techniquesdisclosed herein, and thus may avoid the undesirable complexities thatconventional deposition techniques may impose. Embodiments disclosedherein also may be used, for example, to optimize the cavity of a topemission architecture in which only common-thickness organic layers areused outside the emissive layer or layers, such as where the emissivelayer is to be patterned by OVJP.

In some embodiments, various layers for individual sub-pixels can beproduced using the same mask and/or printing technique that is used todeposit the emissive layer. For example, assuming the same resonant nodefor each sub-pixel, the blue optical stack will be the thinnest,followed by green, yellow and red in order of increasing thickness. Theblue sub-pixel can be tuned optically by using the same mask and/orprinting technique to pattern the HTL for the blue sub-pixel as is usedto deposit the blue emissive layer. A similar approach can be used forother sub-pixels, such as a green sub-pixel formed from a yellow OLEDdeposition as disclosed herein. In such a configuration, additionaloptical thickness may be added to optimize yellow and red sub-pixels.That is, the yellow sub-pixel HTL thickness may be optimized for thegreen sub-pixel, and additional cavity modifications may be made tooptimize the yellow and red sub-pixels. More generally, a single maskand/or deposition technique may be used to pattern one or more layerswithin a sub-pixel, to obtain an optical path length specific to and/oroptimized for the sub-pixel, while allowing for different optical pathlengths for other sub-pixels within a pixel arrangement.

In an embodiment, different optical path lengths for each sub-pixel maybe formed by patterning an electrode, such as the anode, so that theregion of the electrode under each organic stack of the sub-pixel has adifferent thickness. FIG. 57 shows an example of such a configuration.In the example, the electrode material 5740 under each OLED organicstack 5751, 5752, 5753 may be of different thicknesses. The electrodematerial or materials disposed in a stack with a particular OLED stackor sub-pixel may be referred to as an electrode stack. For example, theelectrode stack under OLED stack 5751 is thinner than the electrodestack under OLED stacks 5752 and 5753. In the example shown in FIG. 57,the organic stacks 5752 and 5753 have the same thickness, resulting indifferent total thicknesses for the corresponding sub-pixels. Incontrast, organic stacks 5751 and 5753 have different thicknesses, butthe corresponding sub-pixels have the same or about the same thickness.Different relative thicknesses may result from different manufacturingprocesses. For example, if the electrode 5740 is patterned and commontransport layers are used across the sub-pixels, the organic stacks maybe approximately the same thickness. More generally, each sub-pixel mayhave the same or different thickness than other sub-pixels, and/or eachorganic stack may have the same or different thickness than otherorganic stacks. The thicknesses of organic layers within each sub-pixelalso may be the same or different, for example, depending upon thedifferent fabrication techniques used to fabricate the various layers.In some embodiments, the total thickness of organic layers within someor all of the sub-pixels in a pixel may be the same. In general, twolayers or stacks may be considered to have the same thickness, and/ortwo optical path lengths may be considered to be the same, if one iswithin 3%, 2%, or 1% of the other. For example, if a first organic stackhas an optical path length that is not more than 3% higher or lower thana second organic stack, then the first and second stacks are consideredto have the same optical path length. Alternatively or in addition, someor all of the same types of organic layers within each sub-pixel may bethe same as in some or all of the other sub-pixels, as illustratedthroughout the present disclosure. For example, the thickness of one ormore transport, blocking, injection, and/or emissive layers may be thesame in one or more sub-pixels within a pixel.

A structure such as shown in FIG. 57 may be fabricated, for example,using repeated depositions of electrode and/or other materials,photoresist, etching, and/or lift off processes to produce separateoptical path lengths for individual sub-pixels. In general, an electrodemay be patterned so that a transparent layer, such as a transparentconductive oxide layer, has a different optical thickness, thusproviding a different optical thickness and path length between theelectrode pad and a reflector as shown in FIG. 57.

Fabrication of structures to provide different optical path lengths andthereby enhance light output from different sub-pixels can beaccomplished by using semiconductor fabrication processes such as liftoff, deposition and etching. These processes may be performed as part ofthe backplane fabrication process, before deposition of the organiclayers. The optical path length may be modified by depositing atransparent layer between the reflector and the organic layers, andadjusting the thickness of the transparent layer for the emissionwavelength of the sub-pixel. Alternatively or in addition, thecomposition of the transparent layer may be modified, for example tomodify the refractive index of the material by changing the ratio of theconstituents. As a specific example, in a Si_(x)N_(y) film, the ratio ofSi to N in the film may be selected to achieve a desired index ofrefraction of the film. Such arrangements may be achieved bycombinations of deposition and wet etch, deposition and dry etch andlift-off deposition. In general, each technique also may make use of apatterned photoresist to define the individual sub-pixel cavities.

In deposition and etching techniques, one or more layers of material aredisposed between a reflective layer and an electrode, to change thethickness of the electrode stack in different regions of the electrode.For example, layers of silicon dioxide and silicon nitride may befabricated on top of a metal reflector layer, under an ITO anode. Theetch chemistries are chosen to have good selectivity between silicondioxide and silicon nitride, so that the underlying layer can be used asan etch stop. As described in further detail, both dry etches and wetetches can be used to obtain the desired optical path length. FIG. 58shows a schematic representation of a group of sub-pixels and a crosssection of the cavity layers beneath the pixels. In the examplestructure, silicon dioxide may be deposited and patterned first,followed by silicon nitride. The silicon dioxide layer then forms anetch stop for the silicon nitride etch. The thickness of the silicondioxide and silicon nitride may be chosen to provide the correct opticalpath length for the individual sub-pixels, such as green and redsub-pixels. Thus, the example shown in FIG. 58 shows regions havingthree different optical path lengths: one where there is no oxide ornitride film over the reflector, one in which there is only a nitridefilm over the reflector, and one in which there is both an oxide filmand a nitride film over the reflector.

As a specific example, a structure as shown in FIG. 58 may be fabricatedby blanket depositing SiO₂ over a substrate and/or reflector layer. Aphotoresist is than patterned over the SiO₂ layer and the SiO₂ layeretched using, for example, buffered HF (wet etch) or NF₃ (dry etch),after which the photoresist is removed. Similarly, a blanked layer ofSi₃N₄ is deposited over the SiO₂ layer and the reflector layer, followedby a layer of photoresist. The Si₃N₄ is then etched using, for example,using H₃PO₄:H₂ONF3/O2/N₂ (wet etch) or NF₃/O₂/N₂ (dry etch). Thephotoresist is then removed, and a blanket layer of ITO or otherelectrode material, shown with hash marks, may be deposited over theremaining layers.

FIG. 59 shows another example structure according to an embodiment. Astructure such as shown in FIG. 59 may be fabricated, for example, byrepeatedly depositing a blanket layers of ITO, patterning a layer ofphotoresist, depositing the next layer of ITO, and performing a lift offtechnique to remove a portion of the prior ITO layer. For example, ITOlayers 5910, 5920, 5930 may be deposited in order, using interveningphotoresist and liftoff techniques between sequential ITO layers.Similar structures, such as shown in FIG. 60, may be obtained by usingthe same general process with different masks for the photoresistlayers. For example, ITO layers 6010, 6020, 6030 may be deposited inorder, using intervening photoresist and liftoff techniques betweensequential ITO layers.

In some embodiments, a common anode structure may be used for multiplesub-pixels and a deposition technique such as OVJP may be used topattern different optical path lengths for different sub-pixels. Forexample, different HTL thicknesses may be used for different colors ofsub-pixels, such as for the yellow and red sub-pixels in a four-colordisplay as disclosed herein. Alternatively or in addition, OVJP can beused to deposit the thicker HTL material in a ‘mask-less’ process. Theconcern over ‘spill over’ from OVJP is a minor issue when consideringusing OVJP to deposit non-emissive regions such as the HTL. In contrastto other conventional uses of OVJP, in embodiment disclosed herein,spill-over into neighboring sub-pixels from OVJP likely has little orminor effect on the neighboring sub-pixel performance. If the HTL isdeposited by OVJP in multiple different thicknesses for differentsub-pixels, impurity issues commonly associated with OVJP deposition maybe mitigated by depositing a common EBL, HBL, or similar layer on theHTL to prevent contact of the EML interface with the OVJP layer. Thecommon layer also may increase the efficiency of separate types ofsub-pixels, such as increasing the external efficiency of yellow and redsub-pixels. Alternatively, a high resolution mask step could addadditional ETL, HBL or other material between one or more emissivelayers and a common ETL or other common layer. If the ETL is depositedby OVJP in multiple different thicknesses any impurity issues associatedwith OVJP deposition can be mitigated by depositing a common HBL on theEML. This prevents contact of the EML interface with the OVJP layer.OVJP techniques as disclosed herein may allow for the fabrication ofdevices such as top emission OLED devices of different colors, whereOVJP is used to selectively deposit the emissive layers. This may allowfor all common transport layers to be employed, thus allowing for eachOLED sub-pixel color to have an optimized optical stack.

More generally and as another example, anode patterning or similartechniques may be used to fabricate regions having different opticalpath lengths. Such a configuration may allow, for example, for saturatedred and green sub-pixels to be formed from a single yellow EMLdeposition without the use of any color filters or other color alteringlayers.

Using the techniques disclosed herein, a full-color pixel arrangementfor use in a device such as an OLED display may be fabricated in whicheach pixel includes emissive regions of not more than two colors,disposed laterally adjacent to one another over a substrate. As usedherein, “laterally adjacent” refers to sub-pixels or regions that arenot disposed in a stack with one another, but may be of differentthicknesses and/or disposed at different points within OLED stacks thatare adjacent to one another relative to a substrate. For example, twoadjacent sub-pixels may both include emissive regions of the same color.Each emissive region may be a different thickness, and may not bealigned perfectly or at all with each other in a direction parallel tothe substrate. Such regions are considered laterally adjacent to oneanother because they are not in a common OLED stack, and because theyare disposed adjacent to one another over a common substrate or otherlayer. Each pixel in the pixel arrangement include multiple sub-pixels,each of which may be configured to emit light of a different color thanother sub-pixels in the pixel, and each of which may have a differentoptical path length than each other sub-pixel in the pixel. For example,a pixel may include red, yellow, green, and/or blue sub-pixels, each ofwhich may have an optical path length configured to optimize output forthe respective color emitted by the sub-pixel. As used herein, the“optical path length” of a sub-pixel or other arrangement refers to theoptical distance within the sub-pixel, such as between a reflectivesurface and an exterior surface of an electrode opposite the reflectivesurface within the sub-pixel. The optical path length refers to thedistance traversable by light within the sub-pixel, and may be weightedfor different indices of refraction of materials within a stack thatmakes up the sub-pixel. Thus, the optical path length of a sub-pixelrefers to the sum of the optical path lengths for each material in thesub-pixel stack between the reflective surface on one side of thedevice, and the transparent surface where light leaves the device on theother, with each optical path length being equal to the product of thethickness of the material and the refractive index of that material.Typically the optical path length excludes the thickness of thesubstrate on which a device is fabricated.

In some embodiments, one or more sub-pixels may have the same, about thesame, or different optical path lengths than one or more othersub-pixels within a pixel. For example, two sub-pixels may have the sameoptical path length when they include some or all common layers betweenthe sub-pixels, possibly with the exclusion of color altering layersdisposed in each sub-pixel. That is, a first sub-pixel may have adifferent optical path length than one, two, or three other sub-pixelsdisposed within the same pixel.

As previously described, different optical path lengths may result fromelectrode stacks disposed in a stack with the organic OLED stack used togenerate light within each sub-pixel. For example, FIGS. 56-60 showexamples of electrode arrangements in which transparent layers and/orelectrode material is arranged to form three electrode stacks ofdifferent heights relative to a substrate. When OLEDs are disposed instacks with the illustrated electrode stacks, they may have differentoptical path lengths due to the different heights of electrode stacks.Alternatively or in addition, the OLED stacks themselves may havedifferent heights, such as where different thicknesses of transportand/or blocking layers are used within each sub-pixel. The combinationof OLED stack height and electrode stack height may result in sub-pixelsthat have the same or different optical path lengths. FIG. 61A shows anexample arrangement in which three example sub-pixels have optical pathlengths that are different, using the example electrode stackarrangement shown in FIG. 59. In the example, each of three sub-pixelsincludes emissive stacks 6101, 6102, 6103, which, when combined with thethree electrode stacks formed by different layers 5910, 5920, 5930,result in three sub-pixels having three different optical path lengths.Similarly FIG. 61B shows a configuration in which two sub-pixels 6131,6132 have the same optical path length, which is different than theoptical path length of a third sub-pixel 6133. Although the examplesshown and described with respect to FIGS. 56-61 use three sub-pixels forclarity, similar arrangements may be used that include four sub-pixelsas disclosed herein.

In an embodiment, a full-color pixel arrangement, such as to providepixels in an OLED device, includes first and second sub-pixels havingemissive regions of the same color, but with the sub-pixels havingdifferent optical path lengths. A third sub-pixel in the arrangement mayinclude an emissive region of a different color. Overall the arrangementand, in many cases, the entire device, may include emissive regions ofexactly two different colors. For example, an OLED display as disclosedherein may include only blue and yellow emissive regions and,accordingly, each pixel arrangement may include only blue and yellowemissive regions.

FIG. 62 shows a schematic representation of such a sub-pixelarrangement, in which an anode patterning technique has been used toform green and red sub-pixels from a single yellow EML depositionwithout the use of any color altering layers. As with other similararrangements of sub-pixels, each sub-pixel may be individually addressedeven though a common cathode is used. As shown in the examplearrangement shown in FIG. 62 and as previously disclosed herein,embodiments disclosed herein allow for full-color pixel arrangementsusing only two colors of EML depositions. In the example shown in FIG.62, blue and yellow depositions are used, but it will be readilyunderstood that other includes two colors of EML deposition. Such anarrangement may be fabricated, for example, by depositing the emissivematerials into emissive regions as shown through a fine metal or otherhigh-resolution mask. An arrangement as shown in FIG. 62 may include anelectrode layer 6210 disposed over a substrate 6200. A first emissivematerial, such as a blue emissive material 6220, may be disposed overone part of the electrode layer 6210. The electrode layer 6210 may bepatterned so as to create regions on which the sub-pixels are arranged.The electrode itself or another layer 6230 disposed over the electrodemay be used to create different optical path lengths for two or moresub-pixels 6201, 6202, 6203. For example, the layer 6230 or theelectrode 6210 may be patterned via lithographic techniques to achievedifferent dimensions for each sub-pixel region.

To fabricate a device as shown in FIG. 62, a patterned layer may bedisposed over a substrate to define the regions over which thesub-pixels will be fabricated. The patterned layer may be placed over anelectrode, or it may be formed from or as part of the electrode. Forexample, an existing electrode may be patterned via photolithography orsimilar techniques to create regions as shown in FIG. 62, over whichindividual sub-pixels may be fabricated as otherwise disclosed herein.

In some embodiments only three sub-pixels may be present, while othersmay use four or more, each of which may have the same or differentoptical path lengths as the others. A second emissive material, such asa yellow emissive material 6240, may be disposed over the patternedelectrode regions. The different optical path lengths for the differentregions thus provides multiple, different-color sub-pixels, such asgreen, yellow, and red sub-pixels in this example, respectively. Moregenerally, a full-color pixel arrangement as disclosed herein and asillustrated in FIG. 62 may include N total sub-pixels having emissiveregions of the same color, and N+1 or more total sub-pixels. In someembodiments, it may be preferred for the pixel arrangement to includeN+1 or N+2 total sub-pixels. The arrangement may not include any coloraltering layers or, more generally, may include 0 to N−1 color alteringlayers. As described in further detail herein, although color alteringlayers are not necessary to achieve a full-color pixel arrangement, theymay provide additional benefits in some embodiments.

A second electrode 6250, capping layer 6260, and/or other layers may bedisposed over the emissive materials 6220, 6240. Other layers may beincluded in each sub-pixel device, as disclosed herein and as otherwiseknown in the art.

As a specific example, FIG. 63A shows an example structure of asub-pixel device with a specific structure. To consider the effect ofanode patterning as previously described, the 1931 CIE emissioncoordinates may be modeled as a function of the anode thickness. FIG.63B shows the results of such modeling for the structure shown in FIG.63A. As illustrated, saturated green and red colors are achieved, aswell as a range of yellow color points, for a fixed capping layer (CPL)thickness. The vertical G, Y, B lines in FIG. 63B correspond to thecolor points that generate the spectra shown in FIG. 64, which shows themodeled normalized emission intensity as a function of wavelength forthe yellow EML. This corresponds to the expected emission for green,red, and yellow sub-pixels as previously described in an examplesub-pixel system having the structures shown in FIGS. 62 and 63A.

The use of only two colors of emissive regions also may provide otherbenefits. For example, the white point of a device having this structuremay be tunable by modifying the yellow sub-pixel color point, such as byusing electrode patterning techniques as described above. For example,FIG. 65 shows a schematic illustration of a range available for thewhite point of such a device, by modifying the yellow point of theyellow sub-pixel color point using anode patterning as shown in FIG. 62.

Embodiments disclosed herein may allow for tuning across a wide gamut,and/or matching to a desired gamut or spectrum. Furthermore, embodimentsdisclosed herein may be implemented using a variety of physicalarrangements. For example, anode patterning as previously described maybe used to provide multiple sub-pixels of different colors using asingle color of emissive region or regions. As another example and asdisclosed herein, other layers within the sub-pixel structure, such astransport layers, may be varied to produce different optical pathlengths within different sub-pixels. FIG. 66 shows experimental resultsfor a yellow EML containing e-host, h-host, one red emitter, and onegreen emitter, with the normalized intensity measured at normalincidence. The CIE coordinates of the two peaks are provided, showingsaturated DCI-P3 green and red. Emission for the device was tuned usingthe HTL thickness for each sub-pixel, which provides a cavity-basedequivalent to tuning with a patterned electrode thickness as previouslydisclosed. As another example, FIG. 67 shows the emission profile of asimilar device at normal incidence with the same yellow EML, tuned fromyellow to red emission using varying HTL thicknesses. As shown, the sameyellow EML deposition can be used to provide green, red, and yellowcolor coordinates.

As previously described, an emissive region or layer may include one ormore individual emitters, i.e., materials that emit light whenactivated. For example, a yellow emissive region may include only ayellow emitter, or it may include red and green emitters such that thelight emitted by the emissive region is yellow. A patterned electrode,cavity structures formed from an HTL or similar layer, and othertechniques disclosed herein for achieving different optical paths may beused regardless of the specific content of the emissive materials used.For example, FIG. 68 shows experimental results for a yellow EMLincluding an e-host, h-host, and one yellow emitter tuned from yellow tored using varied HTL thicknesses to produce cavity effects equivalent totuning using various patterned electrode thicknesses, as previouslydisclosed. As shown, green, red, and yellow coordinates are achievablefrom a single color of emissive material.

Embodiments disclosed herein may provide relatively accurate andsaturated color for many emitted colors, using a variety of emitters andconfigurations. For example, FIG. 69 shows the integrated intensity as afunction of angle (FIG. 69A), angle dependent EL (FIG. 69B), 1931 CIE asa function of angle (FIG. 69C), and the 1931 Δv as a function of anglefor a yellow EML composed of e-host, h-host, and 1 green and 1 redemitter at a fixed HTL thickness (FIG. 69D). In this example, the cavityis tuned for red emission. As another example, FIG. 70 shows the samedata for a cavity tuned for red emission for a yellow EML composed ofe-host, h-host, and 1 yellow emitter at a fixed HTL thickness. FIG. 70Ashows the integrated intensity as a function of angle (70A), angledependent E (70B), 1931 CIE as a function of angle (70C), and the 1931Δuv as a function of angle (70D). This example cavity is also tuned forred emission. As another example, FIGS. 71A-D show the same data asFIGS. 69 and 70, for a yellow EML composed of e-host, h-host, and 1green and 1 red emitter at a fixed HTL thickness, tuned for greenemission.

It is well known that microcavity OLEDs blue shift as a function ofangle. The result is that a saturated red microcavity OLED generallywill have more green content as the angle is increased from normalincidence. However, in this case the green sub-pixel microcavity devicedoesn't exhibit as much color shifting with angle as the red sub-pixelas there is no emission from the emissive region which is higher energythan green emission. This can be seen by comparing the Δuv in FIGS. 70and 71. To reduce the colorshifting of the red (or red and yellow)sub-pixels a color filter may be added to reduce or eliminate the greencontent at higher angles. However, the number of color altering layersusing this approach still allows for the use of fewer color alteringlayers than is required by previous approaches, which have relied onusing a color altering layer to produce both green and red sub-pixels.Embodiments disclosed herein thus have an advantage in fabrication andcost over arrangements that use white OLEDs with color filters toachieve full-color devices, because the number of color filters used isless than the number of sub-pixels. Alternatively, a display asdisclosed herein may be used in an application where off-angle coloraccuracy is not important, as is the case for virtual reality andmicrodisplays, in which case no color filters may be used.

In some cases, it may be desirable to include a color filter or othercolor altering layer with a sub-pixel arrangement that includes apatterned electrode and different optical path lengths. FIG. 72A shows amodeled EL spectrum of a red sub-pixel as previously described at 0 and60 degrees, with and without a red color filter as indicated. The changein color (Δuv) is shown in FIG. 72B as a function of angle with andwithout the red color filter as indicated. As shown by these models, theuse of a color filter may allow the spectrum of a sub-pixel to befurther shifted in a desired direction (e.g., more toward red as shownin FIG. 72A). A color filter also may reduce the change in apparentcolor for different viewing angles, as shown in FIG. 72B.

Embodiments disclosed herein also may provide white light, such as whenblue and yellow emissive regions are used. For example, FIG. 73A shows amodeled EL spectrum from sub-pixel generated from a yellow EML using apatterned electrode as previously described. FIG. 73B shows a white EMLusing the same optical microcavities at normal incidence. The sub-pixelcolor and 1931 CIEx and CIEy coordinates are in brackets next to therelevant spectrum. Notably, it can be seen that the microcavity for thered sub-pixel couples both to red emission and blue emission from thewhite emission region. This may significantly lower the color purity ofthe red sub-pixel compared to the red sub-pixel render from the yellowEML as shown in FIG. 73A. As another example, FIG. 74A shows a modeledEL spectrum from sub-pixels generated from a yellow EML, and FIG. 74B awhite EML, using the same optical microcavities at 60 degrees fromnormal incidence. The sub-pixel color and 1931 CIEx and CIEy coordinatesare in brackets next to the relevant spectrum. Once again, it can beseen that the sub-pixels rendered from the white emission region are notspectral pure as they couple to the blue emission. This may result insignificant loss in color purity for both the red and green sub-pixelscompared to the sub-pixels rendered from the yellow emission region.

As disclosed herein, each sub-pixel in an arrangement in whichsub-pixels have different optical path lengths may include other layersand features. For example, a sub-pixel may have an optical path lengthconfigured to optimize output of the pixel for a particular coloremission, such as yellow. However, the sub-pixel may be used to emit adifferent color light, such as green light. To do so, a color alteringlayer may be disposed in a stack with the yellow emissive region, in asub-pixel having an optical path length optimized for yellow emission.Thus, as disclosed herein, multiple sub-pixels may have the same coloremissive region, and may have path lengths optimized for that color,while still being configured to emit light of different colors.

The use of optimized optical path lengths for one or more sub-pixels asdisclosed herein may be advantageous when top emission and/or cavitydesigned OLEDs are used, for example, with configurations as shown inFIGS. 36-39, 41-43, 46-51, and throughout the present disclosure.Furthermore, arrangements that allow HTL or other layer materials to bedeposited in a striped, cross-hatched, or similar configurations mayfacilitate deposition of different optical path-length pixelarrangements using techniques such as OVJP. As a specific example,configurations such as illustrated in FIG. 25 may be fabricated usingOVJP deposition techniques, while achieving different optical pathlengths for the different sub-pixels.

Alternatively or in addition to the arrangements previously described,embodiments disclosed herein may provide OLED structures that includeonly two colors of emissive regions and/or arrangements that includefour or more sub-pixels within each pixel of a full-color OLED display.Additional colors beyond those emitted by the emissive regions may beachieved, for example, by use of color altering layers as disclosedherein.

For example, some embodiments provide architectures and methods forconstructing a superposition and/or spatial color synthesis OLED pixelarchitecture. In such an embodiment, one color of OLED deposition may belocated adjacent to and/or in a separate plane from one or more otherdepositions and/or the substrate. FIG. 24 shows an example schematicarrangement in which yellow (“Y”) sub-pixels are located in a separateplane with respect to the substrate and blue (“B”) sub-pixels. In thisconfiguration, either the Y sub-pixels or B sub-pixels may besubstantially transparent. Red and green color altering layers then maybe superposed over a portion of each of the yellow sub-pixels to renderred and green in the final device.

An architecture such as shown in FIG. 24 may have several advantagesover a conventional side-by-side pixel arrangement. For example, it mayallow the fill factor of blue sub-pixels to be maximized to increasetheir lifetime. The blue sub-pixels may also be microcavities asdisclosed in further detail herein, such as top-emission (TE) OLEDscombined with a substantially Lambertian emission Y sub-pixel plane.Such a configuration may allow the blue spectrum to be manipulated forcolor saturation and efficiency, while minimizing the negative angulardependence issues associated with a full color display where all thesub-pixels are top-emitting, i.e., color shift and image distortionsthat occur as a function of angle. For a given resolution, the lifetimeof yellow sub-pixels, including the red and green color-alteredsub-pixels, also may be enhanced, as the aperture ratio for these pixelsmay be higher since there are only 3 sub-pixels per plane instead of 4.The ratio of yellow, red, or green sub-pixels to blue also may begreater than 1, i.e., there may be more than 1 yellow, red, or greensub-pixel for each blue. An example of such a configuration is shown inFIG. 25, in which there are multiple yellow, red, and green sub-pixelsin each pixel that includes a single blue sub-pixel. The displayresolution will then be determined by the Y(RG) (i.e., yellow emissiveregion with red and green color altering layer) sub-pixels. Such aconfiguration may be acceptable for full-color OLED displays and similardevices, because the human eye typically has relatively poor spatialresolution in the blue region of the spectrum and thus is relativelyinsensitive to the luminance of the blue sub-pixel. Although FIG. 25illustrates a configuration in which the blue sub-pixel has the samearea as the combined Y(RG) sub-pixels, it will be understood that otherconfigurations may be used in which the blue and yellow emissiveregions, and/or the blue, red, and green sub-pixels, have differentrelative sizes.

The two planes of OLED sub-pixels may be constructed in a variety ofways. For example, in the Y(RG)B display, the Y(RG) sub pixels and Bsub-pixels may be fabricated on separate backplanes and then attachedtogether, with one of the backplanes being substantially transparent.Alternatively, the OLED planes may be fabricated on top of one anotherover one backplane.

Another way of fabricating OLEDs on two different planes is for the bluesub-pixel to be approximately the same size as the yellow sub-pixel onthe second plane, so that blue light from the first plane is not lostand absorbed by the red and green color filters of the second plane.This will still result in higher fill factor displays than putting allfour colors in one plane. As red and green are only required to makehighly saturated colors, these sub-pixels typically can be relativelysmall compared to the yellow and blue sub-pixel areas.

FIG. 26 shows an example device configuration having two planes ofsub-pixels. The two planes include blue and yellow emissive regions.Green and red are rendered by the use of color altering layers disposedin a stack with portions of the yellow emissive region or regions. Inthe example shown in FIG. 26, a center electrode is common to bothplanes of sub-pixel emissive regions.

FIG. 27 shows an example top-emitting device configuration having twoplanes of sub-pixels. As with the example shown in FIG. 26, red andgreen are rendered through the use of color altering layers disposed ina stack with portions of the yellow emissive region or regions. In theexample shown in FIG. 27, a passivation layer is disposed between theplanes of sub-pixel emissive regions.

More generally, embodiments disclosed herein may include two emissivelayers of different colors, with only a portion of one emissive layersuperposed with a second emissive layer. As used herein, two layers orregions are “superposed”, or one layer or region is “superposed” withanother, if one layer is disposed above or below the other, relative toa substrate or similar reference. Thus, as previously described, onelayer that may be described as “above” or “below” another layer, orcloser to the “top” or “bottom” of a device than another layer, also maybe described as being “superposed” with that layer. A color alteringlayer may be superposed with a portion of the second emissive layer. Forexample, as previously described, yellow and blue emissive regions orlayers may be superposed within a device, and one or more color alteringlayers may be superposed with a portion of the yellow emissive layerthat is not superposed with the blue emissive layer, relative to asubstrate. Additional color altering layers may be superposed with otherportions of the second emissive layer, such as where red and/or greencolor altering layers are superposed with a yellow emissive region. Inan embodiment, the device may include emissive layers or regions ofexactly two colors, and the device may emit light of at least fourcolors.

As previously described with respect to the example devices includingsuperposed blue and yellow layers, one layer may act as a hole transportor similar layer relative to the emission of the other layer, i.e., thelayer may act to transport holes for recombination within the firstlayer, while generating little or no emission itself, in the region thatis superposed with the first layer. An intervening electrode and/or apassivation layer may be disposed between the two layers, as previouslyshown in and described with respect to FIGS. 22-23. Thus, as previouslydescribed, an emissive region of one color may include some or all of alayer that may provide the emission for that color in an emissive regionelsewhere in the device, while contributing to the ultimate emission ofan emissive region of another color in a different portion of a device.

Embodiments of the invention disclosed herein may use a variety of driveschemes. In many embodiments, four sub-pixels may be available to rendereach color. Typically, only three sub-pixels may be needed to render aparticular color; thus there are multiple options available for theelectrical drive configuration used to render the color. For example,FIG. 12 shows the 1931 CIE diagram with coordinates for pure red, green,and blue, and for a multi-component yellow source that lies outside theRG line according to an embodiment disclosed herein. In a four sub-pixelarrangement as disclosed herein, when rendering a color in the GBY space1210, the red sub-pixel is not required; similarly, if the color to berendered is within the RBY space 1220, the green sub-pixel is notrequired. FIG. 13 illustrates an example color point rendered withoutthe use of a red sub-pixel, i.e., a point which lies within the GBYspace 1210 in FIG. 12. As shown the initial contribution of pixels forthe example point may be R₀, G₀, B₀ for the red, green, and bluesub-pixels, respectively, in a RGBY arrangement. In an RGBY arrangementas disclosed herein, the equivalent contributions for yellow, green, andblue sub-pixels may be Y′, G′, B′, respectively. Notably, the redsub-pixel need not be used to render the desired color.

Another drive arrangement according to embodiments disclosed herein isto fix a white point using yellow and blue sub-pixels. A desired colormay then be rendered through use of the green or red sub-pixel,depending on whether the color lies within the GBY or RBY space. FIG. 14shows a CIE diagram that identifies red, green, blue, and yellow pointsas previously disclosed. A white point 1404 may be established along theBY line using a combination of only the blue and yellow sub-pixels, asshown. A color point 1400 falling in the GBY space, i.e., on the greenside of the BY line, thus may be rendered by using the green sub-pixelin addition to the blue and yellow sub-pixels. Similarly, a point in theBYR space, i.e., on the red side of the BY line, may be rendered usingthe blue, yellow, and red sub-pixels. Thus, embodiments disclosed hereinallow for a variety of drive arrangements, and may provide additionalflexibility, efficiency, and color range compared to conventional RGBWand similar arrangements.

An emissive region, layer, or device disclosed herein may be asingle-layer emissive layer, or it may be a stacked device. Eachemissive region, layer, or device may also include multiple emissivematerials which, when operated in conjunction, provide the appropriatecolor light for the component. For example, a yellow emissive region mayinclude both red and green emissive materials in an appropriateproportion to provide yellow light. Similarly, any emissive region ordevice may be a stacked device or otherwise include emissive sub-regionsof sub-colors that are used to provide the desired color for the regionor device, such as where a stacked configuration with red and greendevices is used to provide a yellow emissive region. Each also mayinclude multiple emissive materials that provide light of the same coloror in the same region. Further, each emissive material used in any ofthe configurations disclosed herein may be phosphorescent, fluorescent,or hybrid, unless indicated specifically to the contrary. Although asingle emissive region as disclosed herein may include multiple emissivematerials, it may be described as emitting only a single color, sincetypically it will not be configured to allow for only one of theemissive materials to be used. For example, a yellow emissive region mayinclude both red and green emissive materials. Such a region isdescribed herein as a yellow emissive region and is considered asingle-color emissive region, since the red and green emissive materialscannot be activated independently of one another.

According to embodiments of the disclosed subject matter, a pixelincluding at least four sub-pixels may be driven based on projectionsassociated with a color signal. The sub-pixels may correspond to orinclude emissive regions containing two or fewer colors, such as a blueemissive region and a yellow emissive region. Multiple sub-pixels may beformed from a single emissive region as previously described, such as bythe use of color altering layers optically coupled to portions of one ofthe sub-pixels. Such a pixel arrangement may include no more than twocolor altering layers.

In operation, a color signal that defines or otherwise provides anintended color to be generated by the pixel is used to drive the pixel.As an example, a display containing thousands of pixels may beconfigured to display an image of an automobile at a given time. Aparticular pixel may be located in an area of the display such that, todisplay the automobile, the intended color output by the pixel is anorange represented by the hex value #FFA500. Instead of driving all foursub-pixels, three of the four sub-pixels may be driven such that thelight that would have been emitted by a primary color sub-pixel in aconventional display (e.g., a green sub-pixel) may be emitted instead bya secondary color pixel (e.g., a yellow sub-pixel). Further, of thethree of four sub-pixels that are driven, a primary color sub-pixel(e.g., a red sub-pixel) may be driven at a lower magnitude based on asecondary sub-pixel (e.g., the yellow sub-pixel) emitting a portion ofthe light that the primary color sub-pixel (e.g., red sub-pixel) wouldhave emitted if driven without the secondary sub-pixel.

As disclosed herein, a color space may be defined by one or moresub-pixels. A color space may correspond to the range of colorsavailable based on the color emission range of one or more sub-pixels.An example of a three sub-pixel color space is shown in FIG. 18. Thethree axes (Red, Blue, and Green) represent the color space availablebased on the three respective red, blue, and green sub-pixels, as shownby the box 1800. Notably, any color point within the color space box1800 may be emitted by driving the Red, Blue, and Green sub-pixels atlevels corresponding to the projection of the color point onto eachrespective sub-pixel. An example of a two sub-pixel color space, such asa “slice” of the color space illustrated in FIG. 18, is shown in FIG.20a . Here the x axis 2020 is represented by the emission capability ofa red sub-pixel and they axis 2010 is represented by the emissioncapability of a green sub-pixel. Notably, any color point within thecolor space represented by the two axes may be emitted by driving thered and the green sub-pixel at levels corresponding to the projection ofthe color point onto each respective sub-pixel. As a more specificexample, a color point 2030 within the color space represented by thered and green color space may be projected onto the red axis as shown byprojection 2032 and may be projected on to the green axis as shown byprojection 2034. The color point 2030 may be emitted by driving the redsub-pixel at a value corresponding to 2033 (i.e., the projection pointof the color point 2030 onto the red sub-pixel axis) and the greensub-pixel at a value corresponding to 2031 (i.e., the projection pointof the color point 2030 onto the green sub-pixel axis). As an example ofa single sub-pixel color space is shown in FIG. 20b . Here, the onlyaxis 2040 corresponds to the emission capability of a red sub-pixel.Notably, any color point within this red pixel's color space may berepresented by a point on the axis 2040. As a specific example, point2045 is a color point that can be emitted by driving the red sub-pixelat the point 2045 itself. It will be understood that the same sub-pixelor sub-pixel type used to show the single sub-pixel color space may be apart of the double and/or triple sub-pixel color space. As a specificexample, a red color pixel may be have the emission capabilityrepresented in FIG. 20b as the red color pixel in FIGS. 20a and 18.

As previously described, a display pixel as disclosed herein may includeat least four sub-pixels. A projection of an original color signal ontoa color space defined by two of the four sub-pixels may be determined.As an example, one way of producing the color specified in an originalcolor signal is to emit a red, green, and blue light from red, green,and blue sub-pixels, respectively. As disclosed herein, alternatively,the original color signal may be projected onto a color space defined bytwo of the sub-pixels such as, for example, the red and the green colorspace. Notably, the projection of the original color signal onto a colorspace defined by two of the sub-pixels may correspond to the magnitudeof emission, corresponding to the two sub-pixels, required to emit theportion of the original color signal corresponding to the twosub-pixels.

FIG. 18 shows an illustrative example of projecting an original colorsignal onto a color space defined by two sub-pixels. As shown in FIG.18, an original color signal may be represented by point 1810. The point1810 may indicate that the original color signal is one that can beemitted by driving the red, green, and blue sub-pixels based on thedirection and magnitude of the point 1810. As disclosed herein, toproduce the specified color using two sub-pixels, a projection of theoriginal color signal onto the color space defined by the red and greensub-pixels, may be determined. This projection may be represented by thefirst projection vector 1802 as shown in FIG. 18. Projecting theoriginal color signal onto the red and green color space may result in acomponent of the original color signal that is based only on the red andgreen color space. In other words, the projection represents thered/green component of the original color signal.

As previously described, a color space also may be defined for a singlesub-pixel. As shown in FIG. 20b , a color space for a single sub-pixelmay be represented by a line as the color space is only singledimensional (as a result of being defined for driving a singlesub-pixel). The color space for a single sub-pixel may be for a primarycolor (e.g., blue, green, red) or may be for a secondary color such asyellow, magenta, cyan, or the like. As an example, a yellow sub-pixelmay have a color space that is a factor of red and green color spaces.As an illustrative example, as shown in FIG. 18, the y-vector 1803represents the color space for a yellow sub-pixel. As shown, the colorspace for the yellow sub-pixel can be represented by points within thered green color space such that the red and/or green sub-pixel may bedriven to emit the color points represented by the yellow color space.

After determining the first projection of the color signal, a secondprojection of the first projection onto a color space defined by asingle sub-pixel may be determined. The color space defined by thesingle sub-pixel may be for a sub-pixel associated with a secondarycolor such that the secondary color is within the color space of twoother sub-pixels in the pixel onto which the first projection wasdetermined. In other words, the color space for the single sub-pixel maybe a combination of at least two other colors emitted by two otherrespective sub-pixels in a pixel. As an example, the second projectionmay be onto a color space defined by a yellow sub-pixel such that thelight emitted by the yellow sub-pixel may be light that is within thecolor space of the red and green sub-pixel. In an illustrative example,as shown in FIG. 18, the color space for a yellow sub-pixel may bedefined by the Y-vector 1804. As shown, the Y-vector 1804 may representthe color space defined by a yellow sub-pixel. The first projectionrepresented by the first projection vector 1802 may have an end at point1811. The first projection vector 1802 may be projected on the Y-vector1804 such that the second projection corresponds to point 1805 on theY-vector 1804.

A second projection of a first projection may represent a singlesub-pixel vector that corresponds to components of both components ofthe two other sub-pixels that the two sub-pixel color space isassociated with. As an example, as shown in FIG. 18, the projection ontothe Y-vector represented by point 1805 represents a color pointassociated with both red and green components of the first projection.In this example, the point 1805 represents the entire green component ofthe first projection vector and represents the entire red component lessthe R-vector 1803 (i.e., RedComponent−R-vector=Red_portion_of_Y-vector).As a more specific example, the point 1811 of the first projectionvector corresponds to a red value of 200 and a green value of 150 (asshown in FIG. 18). The projection of the first projection vector ontothe Y-vector 1804 results in point 1805. Point 1805 on the Y-vectorrepresents the entire green component (i.e., 150) and represents a valueof 100 for the red component. Here, the R-vector may represent theremaining value of 100 such that the overall red value of 200 isrepresented by the R-vector plus the red component of the Y-vector atpoint 1805.

According to embodiments of the disclosed subject matter, a sub-pixelcorresponding to the second projection may be driven based on themagnitude of the second projection. Driving the third sub-pixel based onthe magnitude of the second projection may result in emission of a lightthat is representative of one or more of the components of the firstprojection onto the color space represented by two color pixels.Continuing the previous illustrative example, as shown in FIG. 18, theyellow sub-pixel may be driven based on the magnitude associated withthe second projection point 1805 such that the yellow sub-pixel emitsall of the green component (150) associated with the first projectionvector 1802 and a portion of the red component (100) of the total redcomponent (200) of the first projection vector 1802. Notably, drivingthe yellow sub-pixel at the magnitude associated with the secondprojection may effectively eliminate the need to drive the greensub-pixel as the green component value (150) is emitted by the yellowsub-pixel. Additionally, driving the yellow sub-pixel at the magnitudeassociated with the second projection may effectively reduce theintensity at which the red pixel needs to be driven to produce thedesired color. The reduction may correspond to the magnitude of theR-vector such that, when aggregated, the red component of the yellowemitted light plus the R-vector equal or are substantially close to thered component of the first projected vector. Such a configuration may bemore energy efficient than a conventional three-color arrangement inwhich each of the red, green, and blue sub-pixels would need to bedriven at levels corresponding to the red, green, and blue components ofthe desired color.

More generally, according to embodiments disclosed herein, at least aone sub-pixel in a pixel may not be activated to emit an original colorsignal. For example, as described above, a desired color may be achievedwithout activating a green sub-pixel at all, by using a yellow sub-pixelto obtain the green component of the desired color. As described above,a second sub-pixel may be driven based on the difference between a firstprojection and a second projection, such as the red sub-pixel in theabove example. A third sub-pixel may be driven based on the magnitude ofthe second projection as previously described, such as the yellowsub-pixel in the above example. Finally, a fourth sub-pixel may bedriven based on the respective color component of the original colorsignal. For example, a blue sub-pixel may be driven at a levelcorresponding to the blue component of a color signal in the exampledescribed with respect to FIG. 18. Notably, there may be no need todrive the first sub-pixel at all, since the third sub-pixel can bedriven at a magnitude that includes the necessary color component of thefirst sub-pixel. Additionally, the second sub-pixel may be driven at areduced level as a result of the third sub-pixel being driven at amagnitude that includes at least a portion of the necessary colorcomponent of the second sub-pixel. Notably, the third sub-pixel may emita color equivalent to a combination of colors emitted by the first andsecond sub-pixels.

According to embodiments disclosed herein, an original color signal maybe defined by three primary colors. For example, the original colorsignal may be defined by red, green, and blue coordinates (R, G, B).Each primary color may have a sub-pixel associated with it.Additionally, a secondary sub-pixel may emit light having colorcoordinates (r′, g′, 0) such that it contains components of both R andG. The secondary sub-pixel may be driven at ((G×r′)/g′, G, 0) where(G×r′)/g′ corresponds to the red color component of the original signal(R, G, B) and G corresponds to the entire green component of theoriginal signal. The red sub-pixel may be driven at (R−(G×r′)/g′, 0, 0),where R−(G×r′)/g′ corresponds to the remaining fraction of R such that(G×r′)/g′ and R−(G×r′)/g′ (i.e., the component of the secondarysub-pixel and the component of the red sub-pixel) in combination areequivalent to R, the red component of the original color signal.Accordingly, between the secondary sub-pixel and the red sub-pixel, boththe R and the G component of the original color signal are covered. Thesub-pixel corresponding to a blue emitted color may be driven at (0, 0,B) such that, among the secondary sub-pixel, the red sub-pixel, and theblue sub-pixel, the original color signal (R, G, B) is reproduced.Notably, the green sub-pixel in this example may not be activated toemit the original color signal (R, G, B). Here, the green sub-pixel inthis example may not be activated because g′/r′ is greater than or equalto G/R, which corresponds to the secondary sub-pixel being capable ofemitting the entire green component but not the entire red component.Described another way, in this case the projection onto the green/redcolor space corresponds to a point lying on the “red side” of the“yellow line”, i.e., the side on which the R-vector illustrated in FIG.18 falls.

As another illustrative example, as shown in FIG. 19, an original colorsignal may be represented by vector 1901 and a first projection of theoriginal color signal may be determined onto the color space defined bythe red and green sub-pixels. The first projection may correspond to thefirst projected vector 1902. A second projection onto the Y-vector 1904may be determined and may correspond to the point 1905 on the Y-vector.The point 1905 may correspond to the entire red component of the firstprojected vector 1902 and a fraction of the green component of the firstprojected vector 1902. The entire green component may be represented bythe point 1905 plus the G-vector 1903, as shown in FIG. 19.

According to embodiments disclosed herein, an original color signal maybe defined by three primary colors. For example, the original colorsignal may be defined by red, green, and blue coordinates (R, G, B).Each primary color may have a sub-pixel associated with it.Additionally, a secondary sub-pixel may emit light having colorcoordinates (r′, g′, 0) such that it contains components of both R andG. The secondary sub-pixel may be driven at (R, (R×g′)/r′, 0) where(R×g′)/r′ corresponds to a fraction of G, the green color component ofthe original signal (R, G, B) and R corresponds to the entire redcomponent of the original signal. The green sub-pixel may be driven at(0, G−(R×g′)/r′, 0), where G−(R×g′)/r′ corresponds to the fraction of Gremaining such that (R×g′)/r′ and G−(R×g′)/r′ (i.e., the component ofthe secondary sub-pixel and the component of the green sub-pixel)combine to form G, the green component of the original color signal.Accordingly, among the secondary sub-pixel and the green sub-pixel, boththe R and the G component of the original color signal are covered. Thesub-pixel corresponding to a blue emitted color may be driven at (0, 0,B) such that, between the secondary sub-pixel, the green sub-pixel, andthe blue sub-pixel, the original color signal (R, G, B) is reproduced.Notably, the red sub-pixel in this example may not be activated to emitthe original color signal (R, G, B). Here, the red sub-pixel in thisexample may not be activated because g′/r′ is less than G/R whichcorresponds to the secondary sub-pixel being capable of emitting theentire red component but not the entire green component. This casecorresponds to that in which the projection lies on the “green side” ofthe Y-vector shown in FIG. 19, in contrast to the point illustrated inFIG. 18.

According to an embodiment of the disclosed subject matter, a secondarycolor sub-pixel (e.g., a yellow sub-pixel) may have a color space thatcan be defined by three or more primary colors. As an example, FIG. 20ashows a color point 2030 which corresponds to a red component 2033 and agreen component 2031. Color point 2030 is defined by two primary colors.Similarly, a color space for a sub-pixel may be defined by two primarycolors. As shown in FIG. 18, the color space for the yellow sub-pixel(Y-vector) is defined within the red green color space. The points onthe yellow sub-pixel color space are all within the red green colorspace. Alternatively, if, for example, a color signal is such that itcontains a red component, green component, and a blue component, it maybe originally emitted by three sub-pixels corresponding to primarycolors. Similar to the color signal that is defined by three primarycolors sub-pixels, a color space for a sub-pixel may be defined by threeor more primary colors. The techniques disclosed herein may be appliedby first projecting the color space, for the sub-pixel defined by threeor more primary colors, onto a color space defined by two colors (e.g,the Y-vector in FIG. 18 would be a projection of the yellow sub-pixelscolor space rather than the actual color space itself). The sub-pixeldefined by three or more primary colors may be driven based on the firstand second projections onto the sub-pixel projection. Additionally, twosub-pixels may be operated at reduced values based on driving thesub-pixel defined by three or more primary colors. As an illustrativeexample, a yellow sub-pixel may have a color space defined by red,green, and blue colors. A projection of the yellow sub-pixels colorspace may correspond to the Y-vector shown in FIG. 18. Based on thetechniques disclosed herein, the green sub-pixel may not be activatedand the red sub-pixel may be driven at a reduced level based on drivingthe yellow sub-pixel at a magnitude associated with a projection ontothe Y-vector. Additionally, the blue sub-pixel may operate at a reducedlevel based on the difference between the yellow sub-pixel's color spaceand the Y-vector (i.e., the projection of the yellow sub-pixel's colorspace onto the red-green color space).

If an original color signal is within the color space of two sub-pixels(i.e., instead of three sub-pixels), only a first projection may beneeded and the original color signal may be emitted using only twosub-pixels. Here, a secondary sub-pixel color space may also becontained within the color space of the same two sub-pixels that theoriginal color signal is in. Accordingly, the original color signal maybe projected onto the color space of the secondary sub-pixel. Thesecondary sub-pixel may be driven based on the magnitude of theprojection. The secondary sub-pixel may be driven such that it containsan entire first color component of the original color signal and aportion of a second color component of the original signal. A differentsub-pixel may be driven to compensate for the remaining portion of thesecond color component of the original signal. Accordingly, only thesecondary sub-pixel and the other sub-pixel may be driven of the atleast four sub-pixels within the pixel.

It will be understood that at any given color signal, a given sub-pixelmay be activated or not activated based on the color signal. As anexample, using the notation introduced previously, when g′/r′ is greaterthan or equal to G/R, then a green sub-pixel may not be activatedwhereas when it is less than G/R, a red sub-pixel may not be activated.It will be understood that for two different color signals, a givensub-pixel may be active or not active. It will also be understood thatalthough colors such as red, green, blue, yellow, magenta, and cyan aredisclosed herein, the techniques disclosed herein may be applied to anycolor signals and/or sub-pixels associated with any colors.

FIG. 56 shows another example of processing conventional display datafor display on an RGBY display as disclosed herein. In general,conventional R′G′B′ data may be received, digitally processed, anddisplayed on an RGBY display as shown. R′G′B′ data, which has beenconventionally digital gamma quantized, may be received by a linearizingfunction 5610. The function applies a desired gamma to convert theR′G′B′ data to linear RGB data, which may subsequently be digitallyprocessed. The RGB data is converted to RGBY data in a Gamut MappingAlgorithm (GMA) 5620, which provides several functions including thecolor vector conversion from RGB color vectors to RGBY color vectorsthat substantially reproduce the same colors. The GMA also may accountfor the fact that an RGB color space and an RGBY color display havediffering color gamuts. The RGBY data is mapped, subpixel and metamerrendered in the SPR function 5630, the result of which is represented asRGBYp. The RGBYp data is received by a gamma correction block 5640,which operates to gamma quantize the linear RGBYp data to R′G′B′Y′p datathat matches the gamma distribution of the available light levels of theRGBY display. The R′G′B′Y′p data is then provided to the RGBY display5650. A specific example of rendering for an RGBY display is providedherein with respect to the example arrangement shown in FIG. 39.Additional information regarding the development and use of filterkernels is provided in U.S. Pat. No. 7,688,335, the disclosure of whichis incorporated by reference in its entirety.

Displays and similar devices as disclosed herein are often fabricatedusing a fine metal mask, as previously described. Such a mask may bereferred to herein as a pixelated mask, since it is scaled to allow forthe deposition of sub-pixels as opposed to large-area depositions. Thatis, the purpose of the pixelated mask is to deposit individual coloremissive regions or layers, such as for use in addressable sub-pixels ofparticular colors, not to differentiate between different panels ordisplays where each opening in the mask is of the size of the displayitself, such as white-emitting panels or displays, which are fabricatedon a large-scale substrate for manufacturing efficiency. A pixelatedmask may be referred to in context in the art as a fine metal mask,though other masks also may be referred to as fine metal masks.Embodiments of displays disclosed herein may be designed and fabricatedusing layouts that may increase the pixelated mask opening size,increase the vertical and horizontal spacing between mask openings, andlead to designs in which the mask resolution may be only half of that ofthe display itself. Further, techniques as disclosed herein may allowfor the fabrication of full-color OLED displays and similar devicesusing only two colors of depositions of emissive material, and/or fouror more colors of sub-pixels. Similar to embodiments previouslydescribed, such arrangements may be achieved, for example, by disposingone or more color altering layers in a stack with one or more portionsof an emissive region to form multiple sub-pixels from a single colordeposition.

Making an accurate pixelated mask, especially for large sizes or highresolution, is relatively difficult. Thus, the mask arrangements, pixelarrangements, and fabrication techniques disclosed herein may providesignificant advantages for manufacturing cost and device yield.Techniques disclosed herein also may lower the resolution requirementsfor UP and OVJP printing. Use of the approaches disclosed herein alsomay allow for fabrication of the same resolution display by printing orotherwise depositing organic stripes of wider width, with greaterseparation between adjacent stripes, than could otherwise be achieved.

FIG. 28A shows an example OLED deposition according to an embodiment. Inthis example, only the OLED depositions used to make the yellow and blueemissive regions are shown. As previously described, red and greensub-pixels may be further defined through the use of color alteringlayers such as color filters disposed over portions of the blue and/oryellow emissive regions. FIG. 28B shows the corresponding pixelatedmask, in which the unshaded areas correspond to openings in the mask.

FIG. 29A shows an example sub-pixel emissive material layout accordingto an embodiment, in which sub-pixels of the same color are groupedtogether in adjacent pixels on the same row. FIG. 29B shows thecorresponding pixelated mask arrangement. As can be seen from the masklayout, the size of the mask openings is increased over those in FIG.28, and the horizontal spacing between mask openings is increased. Sucha configuration may simplify the fabrication and use of the mask.Layouts such as shown in FIG. 29B may be particularly suitable forfabrication using printing techniques, and FIG. 29A may be particularlysuitable for use with printing technologies such as IJP or OVJP, inwhich columns of pixels of the same color can be fabricated relativelyefficiency. For example, comparing FIGS. 28A and 29A, it is apparentthat each stripe in FIG. 29A is double the width and includes only oneemissive region transition per pixel. In addition, wider gaps may beincorporated into the mask and arrangement designs, thus lowering theprinting resolution requirements for the same resolution.

Notably, as described with respect to FIG. 29 and other examplearrangements disclosed herein, the provided fabrication techniques mayallow for only a single emissive region color change per pixel. This maybe advantageous regardless of deposition technique because, regardlessof the technique used, it is necessary to have an alignment tolerancebetween emissive layers or regions of different colors to allow formanufacturing tolerances that ensure the correct emissive material isdeposited on any given sub-pixel area. Conventional RGB displaystypically require three such alignment tolerances per pixel, thusreducing the fill-factor of each sub-pixel and consequently the overalldisplay lifetime. In embodiments disclosed herein, a full-color displaymay be fabricated using only one change in color per pixel, allowing foran increased sub-pixel fill factor while maintaining power efficienciesequivalent or comparable to conventional RGB displays, by not filteringall light emitted by the display.

FIGS. 30A and 30B show another example sub-pixel layout andcorresponding pixelated mask, respectively, according to an embodiment.In this configuration, sub-pixels of the same color are grouped in eachrow, but the yellow and blue OLED depositions and emissive regions arestaggered from one row to the next row, i.e., from row x to row x+1. Theadvantage of this layout is shown in FIG. 30B, which demonstrates thatmask openings may be staggered from row to row, leading to a more rigidmask design since no mask opening is directly parallel to another maskopening.

A notable difference between arrangements as illustrated in FIGS. 29 and30 is that each vertical column in FIG. 30 has sub-pixels of differentcolors, whereas in FIG. 29 each sub-pixel color is in a stripeformation. As described in further detail herein, a staggered layout asshown in FIG. 30 may be implemented by staggering the data lines thatsupply pixel video information so that each external data driver isstill driving pixels of the same color, but on different rows, and ismultiplexed using the scan lines. Each yellow sub-pixel may be dividedinto 2 or 3 sub-pixels, for example to render red and green, or red,green and yellow, using color altering layers such as color filters.Thus, each yellow sub-pixel may have 2 or 3 data lines running throughit, while each blue sub-pixel may have one data line connecting thesub-pixels to the external driver. An example of data lines staggered toavoid shorting is provided in FIG. 35, though other layouts may be used.More generally, in an embodiment the number of data lines required bythe display may be less than three times the number of sub-pixels in thedisplay.

FIG. 31 shows another example sub-pixel layout according to anembodiment. In this configuration, the position of the TFTs and scanlines (shown in hashed shading) is changed for each row. As shown, theTFTs and scan lines may be disposed in the upper half of a sub-pixel forone row, and the lower half for the subsequent row. FIG. 32 shows anexample mask design to implement such a configuration. Notably, eachmask opening can evaporate 4 sub-pixels of the same color at the sametime, halving both the vertical and horizontal resolutions. The changein the TFT and scan line position allows for an increase the verticalspacing between mask openings, as compared to the arrangement shown inFIG. 30.

FIG. 33 shows another example of a staggered layout according to anembodiment. FIG. 34 shows an example corresponding mask arrangement. Thestagger in the mask openings leads to an even more rigid mask design,because no mask opening is directly parallel to another mask opening. Amask design as shown in FIG. 34 provides a pixelated mask resolutionthat is less than half the dpi resolution of an arrangement as shown inFIG. 28, at the same display resolution.

FIG. 35 shows an example of data line formation according to anembodiment, in which scan line layers are arranged to allow for astaggered layout configuration as previously described. In thisconfiguration, data lines of the staggered sub-pixels can be connectedby using the underneath scan line layer.

FIG. 36 shows another example arrangement according to an embodiment. Asshown, this arrangement include half the number of red and greensub-pixels relative to the number of yellow sub-pixels, but maintainsthe same area and number of blue sub-pixels to promote blue lifetime. Inthis configuration, each pixel only has three sub-pixels, as opposed tofour as previously described. Such an arrangement may simplify theassociated electrical design by reducing number of data drivers, andreduces the TFT area and the number of TFTs needed per pixel. Thisallows for improved aperture ratios and display performance. Aconfiguration as shown in FIG. 36 may be advantageous due to theresolution of the eye peaking in the yellow region of the spectrumaround 580 nm, and at lower values for red, green, and especially blue.

FIG. 37 shows a variation on the arrangement shown in FIG. 36 in whichthe blue and yellow sub-pixels may be deposited in pairs, thus allowingfor larger openings in the pixelated mask. For example, a maskconfigured as shown in FIG. 30B may be used to deposit the arrangementshown.

In embodiments as previously described, yellow and blue emissive regionsmay serve as the main colors to drive the white point, allow for a moresaturated red and green, and therefore higher color gamut display, thancould be achieved with comparable power consumption using conventionalarrangements. The use of a yellow emissive region allows for a highcolor gamut display with very saturated green and red, but without thetypical higher power consumption that would be otherwise expected.Generally, the use of a yellow emissive region makes the display powerconsumption independent of the overall display color gamut.

FIG. 38 shows another example arrangement according to an embodiment, inwhich each mask opening is used to deposit emissive material for 4sub-pixels of the same color at the same time in four different pixels.Such a technique allows the mask resolution in both x and y direction tobe half the display resolution, based on the number of openings in themask relative to the number of pixels in the display. Each pixel has 3sub-pixels, so the number of data lines and TFTs is not increased from aconventional display. An arrangement as shown in FIG. 38 may onlyrequire two depositions of OLED emissive material through the pixelatedmask, such as blue and yellow as previously described. An additionalmasked deposition step may be performed for other layers, such as theHTL. Notably, although there are only two colors of emissive regions inthe display, the display includes four primary colors (blue, yellow,green, and red in the illustrated example). As previously described,this may be achieved through the use of color altering layers disposedover portions of the yellow emissive regions to achieve red and greensub-pixels.

FIG. 39 shows an example arrangement according to an embodiment in whichfour neighboring blue sub-pixels are replaced by a single largesub-pixel, relative to the arrangement shown in FIG. 38. Such aconfiguration may be used because the human eye typically has relativelylow resolution for blue light. As shown, the yellow sub-pixels may beplaced closest to the blue sub-pixel. It may be preferred for the widthof the large blue emissive regions to be reduced slightly, to allow forthe yellow to be spaced approximately evenly one pixel spacing apart.Combining each cluster of four blue sub-pixels together into one largeaddressable sub-pixel also reduces the required number of data driversand the number of data lines needed across the display. Thus, the pixelarrangement may include half as many red and green sub-pixels as yellowsub-pixels, and one-quarter the number of blue sub-pixels as yellowsub-pixels. The arrangement shown in FIG. 39 may be fabricated, forexample, by using a mask as shown in FIG. 34. The mask resolution ishalf the display resolution in both x and y direction. In someconfigurations disclosed herein, a relatively large emissive region mayprovide sub-pixel functionality to multiple pixels. In such aconfiguration, the emissive region and associated structure orstructures may be considered as providing a “partial” sub-pixel to oneor more pixels. For example, where a relatively large blue emissiveregion is shared by, or used in conjunction with, sub-pixels in fourpixels, the blue emissive region may be considered as providing ¼ of ablue sub-pixel to each pixel. Thus, in aggregate, the number ofsub-pixels among pixels in a display or a region of a display may beless than the number of colors of sub-pixels in the display or theregion of the display.

As previously described, various techniques may be used to convertconventional RGB data for display on an RGBY display, such as shown inFIG. 39 and other examples provided herein. Referring to FIG. 39 as anillustrative example, a layout 3950 of red sub-pixels 3910, greensub-pixels 3920, blue sub-pixels 3930, and yellow sub-pixels 3940 isprovided. The yellow sub-pixels 3940 may be arranged such that they maybe mapped to incoming pixel data in a one-to-one manner. That is, thatthe yellow component of RGBY data need not be subsampled in the SPRfunction 5630 described with respect to FIG. 56. Further, given thisone-to-one relationship and the fact that the yellow sub-pixels may beused to provide maximum energy efficiency by metamer shifting as muchenergy from the red and green sub-pixels, which use relativelyinefficient color altering layers, to the yellow sub-pixels, the yellowsub-pixels may be used to reconstruct most of the high spatial frequencyimage detail.

The red and green sub-pixels 3910, 3920 may be subsampled such that aninput pixel is mapped to either a red or green sub-pixel, which arearranged in a checkerboard pattern as shown. As such, each red and greensub-pixel may be associated with a single yellow sub-pixel. The red andgreen sub-pixels may be sub-pixel rendered, sampling the R and G colorchannels of the RGBY data in the SPR function 5630 using a “diamondfilter” such as:

0 0.125 0 0.125 0.5 0.125 0 0.125 0

Such a filter may appear to “blur” the resulting image, in which case itmay be sharpened using a filter such as:

−0.0625 0 −0.0625 0 0.25 0 −0.0625 0 −0.0625

The blue sub-pixels may be mapped to four input pixels, thus the filterkernel is a two by two filter with each value multiplied by 25%:

0.25 0.25 0.25 0.25

In the examples provided, the filter kernel represents coefficients inan equation; the positions of the coefficients in each table representthe relative positions of the input pixels being resampled to thesub-pixel reconstructing them. The coefficients are multiplied by thevalue of the input pixel, then summed and used as the value of thereconstruction sub-pixel. Although described with respect to the examplearrangement shown in FIG. 39, one of skill in the art will readilyappreciate that similar or identical techniques may be used for theother pixel arrangements disclosed herein.

FIG. 40 shows an example arrangement of a scan and data line layout forthe sub-pixel arrangement of FIG. 39. Notably, the number of lines issignificantly reduced relative to the arrangement shown in FIG. 35.

In some embodiments, it may be desirable to use three color filters, ortwo color filters and a microcavity, to achieve a full color displayusing a RGB1B2Y architecture, i.e., an architecture having red, green,deep blue, light blue, and yellow sub-pixels. In such an arrangement,light blue and yellow emissive regions may be deposited, for exampleusing only two emissive material depositions through a pixelated mask aspreviously described. In this case, deep blue sub-pixels may befabricated through the use of a color altering layer or a microcavitydisposed in a stack with a portion of each light blue emissive region,shown by the horizontal hashing in FIG. 41. As with the arrangementsshown in FIGS. 38-39, such an arrangement only requires two differentOLED stack depositions, and can use a mask having half the resolution ofthe final display. Each pixel may include four sub-pixels, with thedisplay as a whole including five primary colors of sub-pixels (deepblue, light blue, yellow, red, and green). An arrangement as shown inFIG. 41 may provide improved lifetime relative to conventional RGBdisplays, while having similar power requirements to conventional RGBdisplays. Notably, such an arrangement only uses a long-lifetime lightblue emissive region, by using a color altering layer or microcavity toachieve deep blue sub-pixels, which typically is used for only a smallfraction of the time of the light-blue sub-pixels. The table below showssimulation results for an arrangement in which a light blue emissiveregion is converted to deep blue using a color filter. The unfiltereddevice has a CIE of (0.15, 0.265) and the filtered device deep blue of(0.13, 0.057)

Bottom Emission BD377 (12% EQE BE device): 1931 Integrated IntegratedPhoton Lum. Eff Range CIE radiance luminance radiation cd/A All 0.151,8.88 1998 2.21E+19 19.98 0.265 <490 nm 0.130, 4.48 289 1.05E+19 2.890.057 Ratio 0.504 0.145 0.476 0.145

Previous arrangements achieved a desired white point through the use ofdeep blue and yellow emissive regions, as previously described.Referring to FIG. 44, a yellow suitable for use with a deep blue andyellow arrangement as previously described is labeled as Yellow 1. In aRGB1B2Y as described with respect to FIG. 41, implementation of a whitepoint may be principally achieved by the light blue emissive region, andthus a more reddish yellow, “Yellow 2”, may be used to support the samewhite point. If the yellow emissive region is too reddish, it will nothave a sufficient green component to make a reasonably efficient greenwhen used with a color altering layer to achieve green sub-pixels aspreviously described. This implies a trade-off between a light blueemissive region not being so unsaturated that it requires too reddish ayellow to make a white point and therefore not have sufficient green,and the light blue being significantly less saturated than a deep blue,and therefore having improved lifetime. Simulations indicate that apreferred y coordinate of light blue for the RGB1B2Y architecture shownin FIG. 41 may be in the region of 0.15<y<0.20, or 0.10<y<0.25.

FIG. 42A shows an example variant of FIG. 41, in which four of the deepblue sub-pixels are replaced with a single deep blue sub-pixel to beshared by four pixels. This reduces the number of driving lines and TFTcircuits per pixel from 4.0 to 3.25. The deep blue sub-pixels may beformed in what are non-emissive areas in FIG. 41, so as to not reducethe light blue aperture ratio and thus impact its lifetime. In thisconfiguration, the deep blue sub-pixel may use the same light blue OLEDdeposition as the four neighboring light blue sub-pixels, but with anindependently addressable anode. As previously described, the final deepblue emission may be achieved by using a color altering layer and/or amicrocavity disposed over the light blue emissive material.

As another example, an arrangement as shown in FIG. 42A may befabricated using only two high resolution masking steps using apixelated mask as previously described. For example, depositions througha pixelated mask may be performed for the emissive layer material andfor the hole transport layer material. In some cases, only a single highresolution mask deposition process may be used for only the emissivelayer material. In contrast, a conventional process would require twoOLED depositions (for example, for blue and yellow), and an additionalmasked deposition step for HTL deposition to increase the thickness ofthe HTL for the yellow sub-pixel relative to the blue sub-pixel.

As another example, the light blue emissive material may be evaporatedover the entire display, and the yellow emissive material depositedthrough a pixelated mask over the yellow sub-pixels. In this case theemissive regions for the yellow devices would include a two-band blueand yellow emissive layer. As yellow emitters typically have lowerenergy than blue emitters, excitons in both the blue and yellow bandswill transfer to the lower-energy yellow emitters, and only yellow lightwill be produced from the yellow emissive regions. The blue emissivelayer emits light in the blue sub-pixels, but would act as an additionalHTL in the yellow emissive regions. If the thickness of the blue EMLprovides the additional HTL thickness required to optimize the yellowsub-pixel, then no additional HTL masking may be required, allowing forthe complete display to be fabricated with only one masking step.Similar to previous arrangements, such an architecture may require onlyone or two OLED emissive material depositions, and three or fewermasking steps (for OLED materials and the HTL). The mask may have halfthe resolution of the resulting display, and the display may have 3.25sub-pixels per pixel. The display may include five primary colorsub-pixels (deep blue, light blue, yellow, green, and red), with onlytwo primary emissive region colors (light blue and yellow). Such aconfiguration may provide improved lifetimes and similar powerconsumption requirements relative to a conventional RGB display, whileonly requiring a relatively long-lifetime light blue as opposed to thedeep blue typically required.

Arrangements disclosed herein also may be arranged so as to befabricated more efficiently using specific deposition techniques. Forexample, an arrangement similar to the arrangement shown in FIG. 42A maybe used to allow for efficient deposition by OVJP or similar techniquesby arranging the various emissive regions and/or sub-pixels in columns.FIG. 42B shows an example arrangement suitable for efficient depositionvia OVJP.

FIG. 43 shows a similar configuration according to an embodiment, whichmay be suitable for wearable devices and similar applications, in whichtypical usage may not require a high color-temperature white point, suchas D65 or greater. For applications where a yellowish white (e.g. D30 orD40) is acceptable, the dark blue sub-pixel may be omitted entirely,thus simplifying the display to only 3 sub-pixels per pixel.

FIG. 45 shows a comparison of an example conventional RGB side-by-sidepixel layout to an arrangement as disclosed herein that uses only twoOLED emissive region depositions. Because most conventional displaydeposition approaches typically use patterning techniques to depositindividual colors, a spacing is required between sub-pixels of differentcolors to avoid color mixing. In contrast, because embodiments disclosedherein only require one spacing between sub-pixels of different colorper pixel (as opposed to three in a conventional pixel architecture),the fill factor for each sub-pixel can be much higher. FIG. 45 shows anexample for a 280 dpi display where the example two-depositionarrangement approximately doubles the blue sub-pixel fill-factorrelative to the conventional arrangement. The example shows a 90 μmpixel, with 25 μm between active OLEDs, and assumes that TFTs andbuslines occupy 45 μm horizontally.

The examples described above include arrangements in which various coloraltering layers are disposed over a yellow emissive region to providevarious colors of sub-pixels. However, other arrangements may be usedaccording to embodiments disclosed herein. For example, FIG. 46 shows anexample arrangement according to an embodiment in which a green coloraltering layer, such as a color filter, is disposed over a light blue(“LB”) emissive region to provide a green sub-pixel. The use of a lightblue emissive region in combination with a green color altering layermay provide deeper green color saturations relative to other embodimentsin which a green color altering layer is disposed over a yellow emissiveregion. A configuration as shown in FIG. 46 also may allow for a greaterred color saturation, and/or a higher red efficiency, because the yellowemissive region may be designed to match the light blue white point,without the constraint of matching the green color altering layer aswell. Other arrangements also may be used, such as other patterns ofred, green, light blue, deep blue, and yellow, in which the red andgreen sub-pixels are provided using other combinations of color alteringlayers such as color filters.

Notably, the examples shown in FIGS. 37-43, 46-47, and similararrangements may include only a single color transition among emissiveregions in a horizontal and/or vertical direction between each sub-pixelin any pixel in the arrangement and each adjacent sub-pixel, regardlessof whether the adjacent sub-pixel is in the same pixel or an adjacentpixel. That is, the emissive region of each sub-pixel may be adjacent toeither the same color emissive region (e.g., adjacent red and greensub-pixels, when both are formed from a yellow emissive layer with redand green color altering layers), or to one other color emissive region.However, in each other horizontal and/or vertical direction within thedisplay, each sub-pixel may be adjacent to other sub-pixels that havethe same color emissive region. The horizontal and vertical directionsmay refer, for example, to the scan and/or data line layout directionswithin a display. Thus, for staggered layouts as previously described,there may be only a single color transition among emissive regions ofadjacent pixels in one direction, but not in a perpendicular direction.The feature of having a single color transition within a pixel refers tothe emissive regions within sub-pixels, not to the ultimate coloremitted by the sub-pixels, since adjacent sub-pixels may include one ormore color altering layers while still having a common emissive regionor the same color emissive region within the sub-pixels.

As another example, FIG. 47 shows an arrangement according to anembodiment in which a green color altering layer, such as a colorfilter, is disposed over both the light blue and yellow emissive regionsto produce the green sub-pixel. As with the example shown in FIG. 46, anarrangement as shown in FIG. 47 may provide a deeper green colorsaturation for the green sub-pixel, and/or a deeper red color saturationfor the red sub-pixel since the light blue white point need not bematched to the green color altering layer as well as the red sub-pixel.Other similar arrangements may be used, such as where red, green, and/ordeep blue are provided via color altering layers.

As another example, FIG. 48 shows an arrangement according to anembodiment in which a green color altering layer is disposed over deepblue and yellow emissive regions, i.e., a deep blue emissive region isused instead of light blue as shown in FIG. 47. Such an arrangement mayprovide the same or similar benefits as described with respect to FIG.47.

As previously described, in some applications it may be desirable oracceptable to forego the use of a deep blue sub-pixel, such as forlimited displays where a full color gamut is not required. For example,small, portable, and/or wearable displays may not require a deep bluesub-pixel to achieve an acceptable color output range. FIG. 49 shows anexample arrangement according to an embodiment in which the displayrequires only 3 TFT circuits per pixel, and in which no deep bluesub-pixels are present.

In some cases, it may be desirable to use both light blue and deep bluesub-pixels in combination, using various combinations of two colors ofemissive regions and various color altering layers as previouslydescribed. FIG. 50 shows an example arrangement in which a green coloraltering layer is disposed over a light blue emissive region to providethe green sub-pixel, and which includes deep blue and light bluesub-pixels. As previously described, the deep blue sub-pixels may beprovided through the use of a color altering layer and/or a microcavitydisposed over a portion of the light blue emissive region. FIG. 51 showsanother example according to an embodiment in which a green coloraltering layer is disposed over a light blue emissive region to providethe green sub-pixel, and which includes deep blue and light bluesub-pixels, with a different sub-pixel arrangement compared to FIG. 50.

Embodiments disclosed herein may be fabricated using a variety oftechniques. For example, a pixel or pixel arrangement in a full-colorOLED display may be fabricated using a pixelated mask, such as shown inand described with respect to FIGS. 28-51. Each opening in the pixelatedmask may have an area at least equal to the combined area of two, three,or more of the sub-pixels that are to be deposited through the mask.Similarly, the mask may have a total area of at least the combined areaof two sub-pixels of different colors of light produced by the display.In some embodiments the mask openings may be relatively small comparedto the total area of the mask, such as not more than 5%, 10%, 20%, orthe like.

A common emissive material to be used in multiple emissive regionsand/or sub-pixels may be deposited through the mask, such that thesub-pixels are arranged adjacent to one another on the substrate. Thecommon emissive material may be a material that is to be used to formmultiple stacks within sub-pixels that are addressed as separate anddifferent pixels. As previously disclosed, some embodiments may includeno more than two colors of emissive regions, i.e., they can befabricated using only two OLED depositions through the pixelated mask.For example, as described with respect to FIGS. 28-51, some embodimentsmay include only blue and yellow, or light blue and yellow, emissiveregions.

As previously described, multiple sub-pixels may be fabricated using asingle emissive region or adjacent emissive regions, such as byfabricating one or more color altering layers over the emissive region.For example, red, green, and/or deep blue color altering layers may bedisposed over yellow and/or light blue emissive regions. In someconfigurations, a portion of an emissive region may be left unaltered,i.e., no color altering layers may be disposed over or otherwiseoptically coupled to the emissive region. For example, a yellow emissiveregion may be optically coupled to a red color altering layer and to agreen color altering layer, with the respective portions of the yellowemissive region being separately addressable. A portion of the yellowemissive region also may be left unfiltered so as to provide yellowlight, as previously described. More generally, any emissive region thatprovides emission capable of being converted to one or more other colorsmay be used.

In some embodiments, multiple color depositions may be performed. Forexample, an additional emissive layer may be deposited through thepixelated mask, such as to form additional emissive regions in staggeredconfigurations as previously described. The emissive material depositedmay be any suitable color, such as yellow, deep or light blue, magenta,cyan, or any other color achievable with organic emissive materials.

In some embodiments, not more than two colors of color altering layersmay be used. For example, as previously described, in someconfigurations only red and green color altering layers are used.

Embodiments disclosed herein may allow for relatively veryhigh-resolution displays and similar devices, due to the efficiency withwhich sub-pixels may be fabricated and arranged on a substrate. Forexample, in an embodiment an OLED display may include multiple pixels,each of which includes at least or exactly two OLED emissive materialdepositions of different colors disposed adjacent to one another over asubstrate, as previously described. Such a display may have a resolutionof 500, 600, 700, or 800 dpi, or any resolution therebetween.

As previously described, embodiments disclosed herein may allow for theuse of pixelated masks that may be much more physically robust thanconventional fine metal masks, due to the increased distance betweenmask openings that can be used. For example, as shown in FIGS. 29-39 andas described elsewhere herein, the distance between adjacent openings inthe pixelated mask may be at least twice the distance between adjacentemissive regions of a common color in the display. That is, the distancebetween adjacent openings in a pixelated mask, measured parallel orperpendicular to a scan or data line in the final device defined by themask, may be at least twice the distance between adjacent emissiveregions of a common color, measured along the same direction. Thus,although devices disclosed herein may have relatively high fill factorsand resolutions, the masks used to fabricate the devices may have arelatively large amount of “unused” space, i.e., mask area that does notcontain mask openings.

As previously described, in some embodiments it may be desirable to usea microcavity to achieve one or more colors of sub-pixels, such as wherea microcavity is disposed over a portion of a light blue emissive regionto provide a deep blue sub-pixel. As another example, green sub-pixelsas disclosed herein may include a microcavity as an alternative or inaddition to the color altering layers previously described, to increasethe saturation of the green sub-pixel. Once an OLED is formed in acavity, the optical path length between the anode and cathode has a verystrong effect on the OLED efficiency and performance. Further modelingindicates that additional HTL thickness may be desirable in a stack withthe yellow emissive region relative to the blue emissive region, inembodiments disclosed herein that have only blue and yellow emissiveregions, to allow for green and/or blue microcavity designs.

For example, it may be desirable to have different HTL thicknesses forthe blue emissive region deposition compared to the yellow deposition inconfigurations that use blue and yellow emissive regions. This mayrequire an additional pixelated mask deposition step. Thus, in someembodiments, three masking steps may be used—two for EML deposition andone for HTL deposition. In contrast, a similar configuration wouldrequire five masking steps to fabricate a conventional top-emission RGBside-by-side device (3 for EML deposition and 2 for HTL deposition). Asanother example, an additional HTL may be patterned on the yellow pixelas compared to the blue. More generally, an electrode may be superposedwith the two emissive regions, i.e., one being optically coupled to amicrocavity, and the other not. When the distance between a selectedsurface of the electrode and the one emissive region is measured in adirection normal to the electrode, it may be shorter than the distancemeasured between the same surface and the other emissive region,measured in the same direction.

As another example, in an embodiment an additional HTL may be depositedon yellow and red sub-pixels, and the blue and green sub-pixels may bethe same HTL thickness. In such a configuration, the green sub-pixel maybe disposed adjacent to the neighboring blue sub-pixel. That is, theportion of the yellow emissive region that is used for the greensub-pixel may be disposed adjacent to the blue sub-pixel of an adjacentpixel. To avoid configurations having two yellow sub-pixels adjacent toeach other, the yellow unfiltered sub-pixel may be disposed in betweenthe red and green, as shown, for example, in FIG. 52. A similararrangement is shown in FIG. 53, for a configuration in which a mask ofhalf the resolution is used, and the blue sub-pixels are grouped, aspreviously disclosed. The dashed lines in FIGS. 52 and 53 show the HTLmasking for cavity fabrication as disclosed herein.

As previously described, when a microcavity is used in an OLED stack, itmay change the color output, such as the yellow output, of the stack.According to embodiments disclosed herein, it may be preferred for ayellow sub-pixel to have a color output that lies on a straight linedefined by the blue sub-pixel and the desired white point of the device.This is illustrated by FIG. 44, which shows red, green and blue on a CIEchart, and shows a desired yellow (“Yellow 1”) as lying on the lineconnecting the deep blue to the desired white point. This criteriagenerally results in a minimum overall display power consumption and, inan embodiment, is a preferred mode of operation. Thus, in an embodiment,it may be desirable for a region or sub-pixel coupled to a microcavityto be configured to emit light having 1931 CIE coordinates that lie on astraight line with a selected white point and the coordinates of lightemitted by yellow sub-pixels. More generally, it may be advantageous forthe region or sub-pixel to emit light having 1931 CIE coordinates thatlie within (+/−0.02, 0.02) of any point on a straight line between theCIE coordinates of light emitted by the other region being used to setthe selected white point. In some configurations, it may be desirablefor the white point itself to lie within a 1-step, 3-step, or 7-stepMacAdams ellipse of the Plankian Black Body Locus on the 1931 CIEdiagram between the yellow emission and the blue emission.

Another consideration for configurations that include a microcavity isthat a microcavity typically causes OLEDs to appear as different colorsfor different viewing angles, such that the observed output color shiftswith viewing angle. This is generally not desirable. However, in manycases the blue color required for a saturated deep blue cannot be easilyachieved through just emitter design alone. Often in conventionaldesigns an emitter is selected which has good efficiency and lifetime,and which has a blue but not deep blue output, and then a microcavity isused to produce a very deep blue color. This is especially true fortelevisions and similar applications where high color gamuts aredesired. So while it may be desirable to place the blue sub-pixel withina microcavity, it may not be desirable to place the yellow, green and/orred sub-pixels within microcavities, as this will lead to undesirablecolor shifts with viewing angle. However, it has been observed that withincreasing angle from the perpendicular, reds and greens shift toshorter wavelengths of light, which can cause a blue haze in the whitepoint when viewed off-angle. Thus, in some embodiments, the bluesub-pixel may be placed in a microcavity, whereas the yellow sub-pixelis placed in a non-cavity stack, such as a bottom emission design. Moregenerally, embodiments may include one emissive region or sub-pixel thatis placed in or otherwise optically coupled to a microcavity, andanother that is not. In an embodiment, a bottom emission OLED stack maybe used in conjunction with a reflective cathode and a transmissiveanode using a transparent conductive oxide (TCO). A thin metal may bedisposed either below or above the TCO, with or without an insulatingspacers between the TCO, metal, and OLED stack, such that the thin metalat the anode, in conjunction with the reflective cathode, forms amicrocavity. FIG. 54 shows an example schematic representation accordingto an embodiment in which a thin metal layer is disposed above the TCOwith no spacer layers for the blue sub-pixel, and no thin metal isdisposed between the yellow sub-pixel and the TCO. Thus, the resultingdevice includes a microcavity for the blue sub-pixel, and allows for nomicrocavity for the yellow, red and green emission. Such a configurationmay provide a high color gamut and minimal or no change in color withviewing angle, as there will be little or no color shift in the red,green or yellow with viewing angle.

FIG. 55 shows simulation data for an embodiment including blue andyellow emissive regions, with only the blue region coupled to amicrocavity. The white point shift with viewing angle is shown. Asillustrated by FIG. 55, the color shift is much less than measured fromcommercial displays in which all colors are produced from top emissionOLEDs. Specifically, the results from measuring commercial top emissiondisplays show as much as a +/−0.02 shift in both x and y CIE coordinateof the white point as the viewing angle is increased from 0° to 60°. Incontrast, simulation data for an embodiment as disclosed herein shows agreatly reduced shift, including virtually no shift in the CIE xcoordinate and a shift of only 0.005 in they coordinate. More generally,embodiments disclosed herein allow for a color shift in the 1931 CIEcoordinates of the white point of a display of less than (+/−0.01, 0.01)for all viewing angles between 0° and 60°.

As previously described, the various embodiments and configurationsdisclosed herein may allow for a reduced number of data lines andimproved fill factor and resolution for OLED displays. For example, fora given pixel or pixel arrangement in an OLED display as disclosedherein, the pixel may include at least 2 sub-pixels of different colors,and the device may include at least 3 sub-pixels of different colors.That is, each pixel may be described as having a non-integer number ofassociated sub-pixels, when averaged across the display, and/or whensub-pixels that are shared among pixels are described as a partialsub-pixel. For example, a full-color display may include pixels definedby 2, 3, 4, or more sub-pixels, up to some integer n. However, thedevice as a whole may include 3, 4, or 5 or more sub-pixels of differentcolors, respectively, up to n+1. Further, such a configuration mayrequire only n data lines for each of the plurality of pixels.

As used herein, various components may be used as color altering layersas disclosed. Suitable components include color conversion layers, colorfilters, color changing layers, microcavities, and the like. The dyesused in color conversion layers as disclosed herein are not particularlylimited, and any compounds may be used as long as the compound iscapable of converting color of light emitted from a light source to arequired color, which is basically a wavelength conversion elementcapable of converting the wavelength of the light from the light sourceto a wavelength 10 nm or more longer than that of the light of the lightsource. It may be an organic fluorescent substance, an inorganicfluorescent substance, or a phosphorescent substance, and may beselected according to the objective wavelength. Examples of the materialinclude, but not limit to the following classes: xanthen, acridine,oxazine, polyene, cyanine, oxonol, benzimidazol, indolenine, azamethine,styryl, thiazole, coumarin, anthraquinone, napthalimide,aza[18]annulene, porphin, squaraine, fluorescent protein,8-hydroxyquinoline derivative, polymethin, nanocrystal, protein,perylene, phthalocyanine and metal-ligand coordination complex.

Examples of the fluorescent dye for converting luminescence of from UVand higher energy light to blue light include, but not limit to thestyryl-based dyes such as 1,4-bis(2-methylstyryl)benzene, andtrans-4,4′-diphenylstilbene, and coumarin based dyes such as7-hydroxy-4-methylcoumarin, and combinations thereof

Examples of the fluorescent dye for converting luminescence of from bluelight to green light include, but not limit to the coumarin dyes such as2,3,5,6-1H,4H-tetrahydro-8-trifluoromethylquinolizino(9,9a,l-gh)coumarin, 3-(2′-benzothiazolyl)-7-diethylaminocoumarin,3-(2′-benzimidazolyl)-7-N,N-diethylaminocoumarin, and naphthalimide dyessuch as Basic Yellow 51, Solvent yellow 11 and Solvent Yellow 116, andpyrene dyes such as 8-Hydroxy-1,3,6-pyrenetrisulfonic acid trisodiumsalt (HPTS), and combinations thereof.

Examples of the fluorescent dye for converting luminescence from blue togreen light to red include, but not limit to the perylene based dyessuch asN,N-bis(2,6-diisopropylphenyl)-1,6,7,12-tetraphenoxyperylene-3,4:9,10-tetracarboxdiimide(Lumogen Red F300), cyanine-based dyes such as4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl-4H-pyran,pyridine-based dyes such as1-ethyl-2-(4-(p-dimethylaminophenyl)-1,3-butadienyl)-pyridiniumperchlorate, and rhodamine-based dyes such as Rhodamine Band Rhodamine6G, and oxazine-based dyes, and combinations thereof.

Examples of the inorganic fluorescent substance include, but not limitto an inorganic fluorescent substance comprising a metal oxide or metalchalcogenide doped with a transition metal ion, including a rare-earthmetal ion.

Many metal-ligand coordination complexes can be used as dyes, they canbe both fluorescent and phosphorescent substance.

It may be preferred to use a color conversion layer in the state thatthe layer is stacked on a color filter. The stacked structure thereof onthe color filter makes it possible to make better color purity of lighttransmitted through the color conversion layer. In some configurations,a “color altering layer” as disclosed herein may include multiplecomponents, such as a color filter disposed in a stack with a colorconversion layer, or just a color conversion layer alone, or just acolor filter alone.

The material used for color filters is not particularly limited. Afilter may be made of, for example, a dye, a pigment and a resin, oronly a dye or pigment. The color filter made of a dye, a pigment and aresin may be a color filter in the form of a solid wherein the dye andthe pigment are dissolved or dispersed in the binder resin.

Examples of the dye or pigment used in the color filter include, but notlimit to perylene, isoindoline, cyanine, azo, oxazine, phthalocyanine,quinacridone, anthraquinone, and diketopyrrolo-pyrrole, and combinationsthereof.

As used herein, and as would be understood by one of skill in the art, a“color conversion layer” (e.g. a “down conversion layer”) may comprise afilm of fluorescent or phosphorescent material which efficiently absorbshigher energy photons (e.g. blue light and/or yellow light) and reemitsphotons at lower energy (e.g. at green and/or red light) depending onthe materials used. That is, the color conversion layer may absorb lightemitted by an organic light emitting device (e.g. a white OLED) andreemit the light (or segments of the wavelengths of the emissionspectrum of the light) at a longer wavelength. A color conversion layermay be a layer formed by mixing the fluorescent medium materialcontained in the above-mentioned color conversion layer with the colorfilter material. This makes it possible to give the color conversionlayer a function of converting light emitted from an emitting device andfurther a color filter function of improving color purity. Thus, thestructure thereof is relatively simple.

Embodiments disclosed herein may be incorporated into a wide variety ofproducts and devices, such as flat panel displays, smartphones,transparent displays, flexible displays, televisions, portable devicessuch as laptops and pad computers or displays, multimedia devices, andgeneral illumination devices. Displays as disclosed herein also may haverelatively high resolutions, including 250, 300, 400, 500, 600, 700 dpi,or more, or any value therebetween.

It is understood that the various embodiments described herein are byway of example only, and are not intended to limit the scope of theinvention. For example, many of the materials and structures describedherein may be substituted with other materials and structures withoutdeviating from the spirit of the invention. The present invention asclaimed may therefore include variations from the particular examplesand preferred embodiments described herein, as will be apparent to oneof skill in the art. It is understood that various theories as to whythe invention works are not intended to be limiting.

The invention claimed is:
 1. A full-color pixel arrangement for an OLEDdevice, the full-color pixel arrangement comprising: a first sub-pixelcomprising a first emissive region of a first color and having a firstoptical path length; a second sub-pixel comprising a second emissiveregion of the first color, the second sub-pixel having a second opticalpath length different than the first optical path length; and a thirdsub-pixel comprising a third emissive region of a second color; whereinthe full-color pixel arrangement comprises emissive regions of exactlytwo different colors; wherein the second emissive region providesemission for the second sub-pixel without any intervening color alteringlayers, and wherein the first sub-pixel comprises a first non-emissivelayer having a first thickness and the second sub-pixel comprises asecond non-emissive layer of the same type as the first non-emissivelayer and having a second thickness different from the first thickness.2. The full-color pixel arrangement of claim 1, wherein the first andsecond non-emissive layers are electron transport layers (ETLs), holeblocking layers (HBLs), or capping layers (CPLs).
 3. The full-colorpixel arrangement of claim 1, wherein the first and second non-emissivelayers are hole transport layers (HTLs), electron blocking layers(EBLs), or hole injection layers (HILs).
 4. The full-color pixelarrangement of claim 1, wherein the first sub-pixel comprises a thirdnon-emissive layer having a third thickness and the second sub-pixelcomprises a fourth non-emissive layer of the same type as the thirdnon-emissive layer and having a fourth thickness different from thethird thickness.
 5. The full-color pixel arrangement of claim 4, whereinthe third and fourth non-emissive layers are electron transport layers(ETLs), hole blocking layers (HBLs), or capping layers (CPLs).
 6. Thefull-color pixel arrangement of claim 4, wherein the third and fourthnon-emissive layers are hole transport layers (HTLs), electron blockinglayers (EBLs), or hole injection layers (HILs).
 7. An OLED devicecomprising the full-color pixel arrangement of claim
 1. 8. The OLEDdevice of claim 7, wherein the OLED device is a display having aresolution of at least 250 dpi, 300 dpi, 400 dpi, 500 dpi, or 600 dpi.9. The OLED device of claim 7, wherein the OLED device is a displayhaving a resolution of at least 700 dpi.
 10. The OLED device of claim 7,wherein the device is a type selected from the group consisting of: 1wearable device, a flat panel display, a computer monitor, a medicalmonitor, a television, a billboard, a light for interior or exteriorillumination, a signal, a color tunable or color temperature tunablelighting source, a heads-up display, a fully transparent display, aflexible display, a 3D display, a laser printer, a telephone, a cellphone, a personal digital assistant (PDA), a laptop computer, a digitalcamera, a camcorder, a viewfinder, a micro-display, a vehicle, a largearea wall, a theater or stadium screen, and a sign.